Digitized by the Internet Archive 

in 2007 with funding from 

IVIicrosoft Corporation 



http://www.archive.org/details/essentialsofmediOOmortrich 



ESSENTIALS OF MEDICAL 
ELECTRICITY 



A TEXT/BOOK OF 

RADIOLOGY 

BY 

E. REGINALD MORTON 

M.D., CM. (tRIN. tor.), F.R.C.S. (EDIN.) 

Past President, Section of Electro-Therapeutics, 
Royal Society of Medicine, Lecturer on Radi- 
ology, West London Post Graduate College, 
in charge of X-Ray Department, West 
London Hospital, etc., etc. 

Demy octavo. 237 pages. 26 full-page 
plates and 72 illustrations. Cloth 

"Eminently practical and up-to-date." — 
Archives of the Roentgen Ray. 

"A very valuable addition." — Lancet. 

"Should be on the bookshelf of every naval 
medical o^c&r." ^Journal oj the Royal Naval 
Medical Service. 

"This is an eminently practical book." — Indian 
Medical Record. 

"It is most concise, beautifully illustrated, and 
abounding with useful information." — Edinburgh 
Medical Journal. 

"It is the book of all others to be recom- 
mended." — Universal Medical Record. 

" We can heartily recommend it as a most 
useful guide and a valuable addition to X-ray 
literature." — West London Medical Journal. 



ESSENTIALS 



OF 



MEDICAL ELECTRICITY 



BY 

E. REGINALD MORTON 

M.D. (trin. tor.), F.R.C.S. (edin.) 

Medical Officer in Charge, X-Bay Department, West London 
Hospital, etc. 



THIRD EDITION, REVISED AND REWRITTEN WITH ADDITION 
OF NEW MATTER 



BY 

ELKIN P. CUIVIBERBATCH, m.a., m.b., b.ch., oxon. 

Member of the Boyal College of Physicians of London, Medical Officer 

in Charge of the Electrical Department, St. Bartholomew's 

Hospital, and late Demor^strator of Physiology in 

the Medical Scnool^ 



WITH ELEVEN PLATES AND SEVENTY-TWO ILLUSTRATIONS 



ST. LOUIS 

C. V. MOSBY COMPANY 

1916 



^ 



.^^^; 



.^ 



\p 



y> 



/ 



PREFACE TO THE THIRD EDITION 

Since the appearance of the last edition of the present 
work considerable advances have been made in the 
subject of medical electricity. New and important 
methods have been introduced, while the mode of action 
of electricity in the treatment of disease is now more 
clearly understood. 

The author of the present edition has therefore found 
it necessary to rewrite and rearrange the work so as to 
include the new methods and, at the same time, present 
the subject in the light of the newer and clearer know- 
ledge of the way in which electricity acts in the cure or 
relief of disease. 

The different methods of electrical treatment have 
been considered in separate chapters. The title of the 
book compels the insertion of a chapter dealing with the 
elementary physical principles of electricity, for know- 
ledge of the latter is essential for the successful practice 
of electro -therapy. The chapter deaHng with this part 
of the subject has been placed at the end of the book, so 
that those who have not forgotten the elements of the 
physics of electricity can commence, as soon as possible, 
the chapters dealing with the application of electricity 
for medical purposes. E. P. C. 

15 Upper Wimpole Streist, W. 
1916. 

380586 



CONTENTS 

PAGE 

Introduction .... i 

CHAPTER I 

The Mode of Action of Electricity on the 

Body ..... 3-15 

CHAPTER II 

The Constant Current and its Modifica- 
tions ..... 16-34 

Constant Current — Simple Interrupted Current — 
Simple Alternating Current — Sinusoidal Current — 
Slow Sinusoidal Currents — Faradic Current 

CHAPTER III 

Sources of Electrical vSupply . . 35-63 

Current from the Main — Direct Current — Alternating 
Current — Rectifiers — Dangers attending Use of Main 
Current — Private I nstallation — Accumulators — Prim- 
ary Batteries — Dry Cells 

CHAPTER IV 

The Body as a Conductor of Electricity . 64-70 

Resistance of the Body — Path of Current — Anode and 
Kathode — Conduction of Ciurrents at High Voltage 

CHAPTER V 
Ionic Medication .... 71-87 

Definition — Introduction of Ions into Body — ^Advan- 
tages — Limitations — Penetration — Apparatus — 
Source of Current— Ions used — Practical Application 
— lonisation of Special Parts — Duration of Treatment 
yii 



viii CONTENTS 

CHAPTER VI 

PAGE 

Surgical Ionisation — The Use of the 
Electrical Current for Destruction of 
Tissue ..... 88-98 

Principles — Removal of Superfluous Hairs — Nsevi — 
Monopolar Method — Bipolar Method — Stellate Veins 
— Warts — Moles — Strictures of Urethra — Uterine 
Fibromyomata — Aneurysm — Malignant Growths 

CHAPTER VII 
Ionisation in Deep-Lying Tissues . . 99-103 

CHAPTER VIII 

The Use of the Electrical Current for 
Stimulation of the Tissues ; Electric 
Baths . . . . . 104-117 

Modification of Current for Stimulation of Tissues — 
Application to the Body — Electric Baths — General 
Faradisation or Galvanisation 

CHAPTER IX 

Electrical Treatment of Paralysis . 118-137 

Current — Electrodes — Strength and Duration of 
Treatment — Peripheral Nerve Paralysis — Facial 
Paralysis — Paralysis of Shoulder Muscles — Of Arm 
Muscles — Erb's Paralysis — Peripheral Nerve Paralysis 
in Lower Limb — Infantile Paralysis 

CHAPTER X 

The Use of the Electrical Current for 
Testing the Reactions of Muscle and 
Nerve ..... 138-160 

Normal Muscle and Nerve — How Electrical Testing is 
carried out — Testing Nerve Trunks — Types of Re- 
action — Meaning of Various Reactions — Course of the 
Reaction of Degeneration — Prognosis — Practical Diffi- 
culties — Defects — Testing with Condenser Discharges 



CONTENTS ix 

CHAPTER XI 

PAGE 

High-Frequency Currents . . 161-177 

How Currents are produced — Apparatus — Measure- 
ment — How applied — Action — High-Frequency and 
Surgical Cases 

CHAPTER XII 
Diathermy ..... 178-193 

Production of Currents — Physiological Action — Proof 
of Heating of Deep Parts — How applied — Medical 
Diathermy — Surgical Diathermy — How performed — 
Advantages — Results 

CHAPTER XIII 

The Use of Static Electricity . . 194-213 

Apparatus — Machines — Accessory Apparatus — 
Machine in Action — Methods of Application — Static 
Bath — Static Wave Current — Static Breeze — 
Electrical Sparks — Static Induced Current 

CHAPTER XIV 

Index of Electrical Treatment . . 214-251 

Acne — Acroparaesthesia — Alopecia — Amenorrhoea 
— Anal Fissure — Aneurysm — Aphonia — Arthritis 
— Anterior Poliomyelitis — Asthma — Boils — Car- 
buncles — Cardiac Failure — Chilblains — Chorea — 
Colitis — Congestion — Constipation — Corns — 
Corneal Ulcers — Corneal Opacities — Disorders of 
Digestion — Disseminated Sclerosis — Dupuytren's 
Contraction — Dysmenorrhoea — Endometritis — 
Episcleritis — Exophthalmic Goitre — Fibrositis — 
Fistula — Gonorrhoea — Headache — Hemiplegia — 
High Blood Pressure — H5rpertrichosis — Hysteria — 
Incontinence of Urine — Ingrowing Eyelashes — In- 
somnia — Intermittent Claudication — Keratitis — 
Lachrymal Obstruction — Locomotor Ataxy — Lupus 
— Malignant Growths — Mental Diseases — Meralgia 
Paraesthetica — Metatarsalgia — Moles — Myalgia — 
Myelitis — Naevus — Neuralgia — Neurasthenia — 



X CONTENTS 

Chapter XIV — continued 

PAGE 

Neuritis — Obesity — (Esophageal Spasm — Orchitis 
— Ophthalmia Neonatorum — Optic Neuritis — Ovarian 
Neuralgia — Ozaena — Paralysis — Paralysis Agitans 
— Perineuritis — Piles — Pleurisy — Port- Wine Marks — 
Prostatic Enlargement — Pruritus — Pyorrhoea 
Alveolaris — Raynaud's Disease — Rickets — Rodent 
Ulcer — Scars — Sciatica — Sexual Disorders — 
Sinuses — Spring Catarrh — Sycosis — Synovitis — 
Tinea Tonsurans — Tinnitus Aurium — Trachoma — 
Ulcers — Variocele — Varicose Veins — Writer's 
Cramp — Warts 

CHAPTER XV 
Physical Principles . . . 252-295 

Nature of Electricity — Static Electricity — Conductors 
and Insulators — Induction — Electroscope — Density — 
Capacity — Condensers — Production of Static 
Electricity — Current Electricity — Chemical Methods 

— Voltaic Cell — Dry Cells — Accumulators — Bi- 
chromate Batteries — IVIeasurement — Electro-motive 
Force — Resistance — Unit of Current — Ohm's Law 

— Internal Resistance — Arrangement of Cells — 
Current Density — Magnetism — Galvanometer — 
Electro-magnet — Electro-magnetic Induction — 
Self-induction — Alternating Current — Dynamo — 
Motor Transformers — Static Transformer 



LIST OF ILLUSTRATIONS 

PAGE 

Plates L-XI. — Motor points and cutaneous 
areas .... Facing page i6o 

FIG. 

1. Passage of current through a solution of sodium 

chloride . . . . .5 

2. Passage of current through a solution of sodium 

chloride . . . . .7 

3. Graphic representation of Simple Interrupted 

Current . . . . • ^7 

4. Metronome Interrupter. Baird & Tatlock . 18 

5. Plan of Commutator of Leduc . . 19 

6. Leduc's Mechanical Interrupter. Newton & 

Wright . . . . .20 

7. Ruhmkorff's Commutator . . .21 

8. Graphic representation of a Simple Alternating 

Current . . . . . 22 

9. Graphic representation of a Sinusoidal Current 23 

10. Pantostat. Schall & Son . . .24 

11. Plan of Ewing's Rhythmic Reverser . . 26 

12. Diagram of Primary Circuit of induction coil . 28 

13. Graphic record of the Primary and Secondary 

Currents of an induction coil. H. K. Lewis 
&Co. . . . . • 30 

14. Graphic record of the Secondary Current. H. K. 

Lewis & Co. . . . -31 

15. Lewis Jones' Coil. Schall & Son . '32 

16. Sledge Coil. Schall & Son . • • 33 



xii LIST OF ILLUSTRATIONS 

FIG. PAGE 

17. Current derived from main . . -36 

18. Plan of Shunt Resistance. Schall & Son . 37 

19. Shimt Resistance. Schall & Son . . 39 

20. Morton Box. Schall & Son . . .40 

21. Galvano-faradic Outfit. Schall & Son . 41 

22. Shunt Resistance for Cautery. Schall & Son 43 

23. Scheme for derivation of current from alternat- 

ing current by way of a transformer . 47 

24. Transformer for Light and Cautery. Schall 

& Son . . . .48 

25. Plan showing how shocks maybe accidentally 

derived from main current . . -53 

26. Plan showing how shocks may be accidentally 

derived from main current . . -55 

27. Portable Dry Cell Battery. Cavendish Electrical 

Co. ..... 61 

28. Double Crank Collector. Schall & Son . 62 

29. Diagram to indicate divergent lines of flow 

of constant current through tissues . 66 

30. Diffusion of current . . . -67 

31. Diffusion of current . . . .68 

32. Anode overlying muscle under skin . . 69 

33. Diagram of Electrode . . -7^ 

34. Epilation Needle fixed to Holder. Schall & Son 90 

35. Needles for Electrolysis. Schall & Son . 91 

36. Lewis Jones' Bi-polar Needle. Schall & Son . 92 

37. Bougie Electrode. Schall & Son . . 95 

38. Rhythmic Resistance- varying Device. Watson 

& Sons ..... 107 

39. Rhythmic Resistance- varying Device. Schall 

& Son ..... 108 

40. Schnee Bath , . . . '113 



LIST OF ILLUSTRATIONS xiii 

FIG. ■ PAGE 

41. Paddle Electrode. Schall & Son . .114 

42. Combined Battery. Schall & Son . . 140 

43. Testing Electrode. Cavendish Electrical Co. . 141 

44. D'Arsonval's Transformer. Schall & Son . 162 

45. Plan of High-Frequency Arrangement . 163 

46. Intermittent trains of oscillations . . 165 

47. Hot-wire Milliampere-meter. Schall & Son . 166 

48. High-Frequency Outfit. Schall & Son . 167 

49. Auto-Condensation Couch. Watson & Sons . 169 

50. Vacuum Electrodes. Cossor . . 172 

51. Diagram showing circuits in a diathermy 

apparatus . . . . .180 

52. Diathermy Machine. A. E. Dean . .182 

53. Condenser Couch. Schall & Son . .186 

54. Wimshurst Machine. Newton & Wright . 195 

55. Holtz Machine. Whittaker S- Co. . . 198 

56. Electrodes for use with Static Machine . 201 

57. Static Breeze ..... 204 

58. Arrangement of Apparatus for application of 

Static Wave Current . . . 206 

59. Arrangement of Apparatus for application of 

Static Breeze .... 209 

60. Arrangement of Apparatus for application of 

Static Induced Current . . . .212 

61. Electrode for Enuresis . . . 230 

62. Electroscope . . . . .258 

63. Leyden Jar. Newton cS^ Wright , . 262 

64. Plates and Poles of a Voltaic Cell . . 267 

65. Diagram of Twelve Cells joined in Series . 278 

66. Diagram of Twelve Cells joined in Parallel . 279 

67. Lines of Force around a Bar Magnet . . 282 



xiv LIST OF ILLUSTRATIONS 



FIG. 



68. Milliampere-meter of the "Moving Coil" Type. 

Cavendish Electrical Co. . . .264 

69. Arrangement of Shunts in Milliampere-meter. 

Schall &' Son . . . .285 

70. To illustrate way in which an Alternating 

Sinusoidal Current is produced . . 289 

71. Dynamo constructed to generate a Direct 

Current. General Electric Co. . .291 

72. Plan of a Static Transformer . . 294 



Essentials of Medical 
Electricity 

INTRODUCTION 

The subject of the present volume is the use of electric- 
ity for the treatment of disease. Although the precise 
nature of electricity is unknown, its mode of action on 
the body is now more clearly understood, and it is being 
gradually recognised that its physiological and thera- 
peutic effects are the consequence either of chemical or 
physical changes that it brings about in the tissues. 
The nature of these chemical and physical changes will 
be set forth in Chapter I. In many cases it is quite clear 
how electricity, by bringing about these changes, can 
cure disease or relieve its symptoms ; in others it is less 
evident ; but so long as we look upon the unknown agent 
electricity as an agent which produces known chemical 
and physical effects, we are enabled to see more clearly 
which diseases and morbid conditions are likely to benefit 
and render less empirical their electrical treatment. 

For the practice of medicaL electricity a sound know- 
ledge of physics is necessary, for, without it, the principles 
of the subject and even the meaning of the terms in 
everyday use will not be understood, and it will be im- 
possible to discover and put right simple failures of the 
apparatus when they occur. Those whose knowledge of 
physics has grown grey will find a brief outline of the 
physical principles of electricity and explanations of the 
terms in common use in Chapter XV. 

A I 



2 .- ; KSSENTIAL? or MEDICAL ELECTRICITY 

With the exception of its use in testing the reactions 
of muscle and nerve, electricity deals almost entirely 
with treatment. Of the maladies for which it is used, 
there are some for which it procures cure or relief where 
other methods have failed, or where other methods are 
slower and less efficacious. There are other maladies, 
incurable by any known method, for which electrical 
treatment is still sometimes requested, cases which drift 
down, like derehcts, to the electrical departments of 
hospitals on the chance that some benefit may be derived 
there. There is a third group of maladies comprising 
the diseases of which the symptoms can be relieved by 
electrical treatment. For these, electricity is part of the 
treatment of the disease, and if it is to 3deld the best 
results the general treatment should not be neglected. 
There is, now, no region of the body to which electrical 
treatment is not apphed, and it is essential that the 
practitioner of electro-therapeutics should have a general 
experience of medicine as well as a special knowledge of 
the subject dealt with in the present book, while the 
prescriber should be acquainted with the field of medical 
electricity, so that the treatment may be administered 
only to suitable cases. 



CHAPTER I 

THE MODE OF ACTION OF ELECTRICITY ON THE BODY 

It has been mentioned in the Introduction that the 
physiological and therapeutic action of electricity is due 
to chemical or physical changes which it produces in the 
tissues. The way in which these changes are brought 
about will be best understood by the study of the pass- 
age of an electric current through water containing a 
salt in solution. If two wires leading from the poles 
of a battery are immersed in water without touching, 
and a milliampere-meter is placed in circuit, no current 
will be indicated if the water is perfectly purp and 
contains no salts in solution. The needle of the milli- 
ampere-meter wiU remain at zero. If now a salt such as 
sodiimi chloride is dissolved in the water, the current is 
able to flow and the needle of the milliampere-meter 
moves across the scale. The addition of any other salt 
will produce the same effect, provided it is soluble in 
water. So also will a soluble base (such as sodiimi 
hydrate) or a soluble acid. These bodies, when dis- 
solved, form solutions that enable the current to flow, 
and are known as "electrolytes." In the dry, undis- 
solved condition they do not conduct the electrical 
current any more than the pure water, but in solution 
they undergo change, so that the current is able to pass. 
If, instead of a salt or base or acid, some albumen or 
other soluble protein, free from salts, is dissolved in pure 
water, no current will flow. If starch or dextrine or 
dextrose is dissolved, still no current wiU flow. Pro- 
teins and carbohydrates, and other chemicals such as 

3 



4 ESSENTIALS OF MEDICAL ELECTRICITY 

alcohol and phenol do not, when they pass into solution, 
enable the electric current to pass : they are not electro- 
lytes. The first important point to be observed with 
regard to the passage of the electric current through the 
body is this — ^the tissues conduct the electric current 
because they contain electrolytes — viz. salts in solution. 
The tissue protoplasm and its products are not them- 
selves conductors of this current, but the latter can pass 
through them because they are permeated with fluid 
that contains salts in solution. 

To return to the experiment on the passage of the 
current through the solution of salt. The passage of the 
current is not the only phenomenon observed. Chemical 
changes are at the same time taking place. One of these 
is evident. Bubbles of gas (hydrogen) are seen escaping 
in the region where the current is leaving the solution. 
Other chemical changes are taking place at the same time 
and will be. mentioned in due course. 

It is now necessary to consider more in detail the 
nature of these chemical changes and how they are 
brought about. When an electrol5d;e dissolves in water 
(thereby enabling the current to pass) it undergoes 
certain changes. It is generally believed that in the 
process of solution a certain proportion of the molecules 
divide or dissociate into two parts, each part taking an 
electrical change. These electrically charged parts are 
known as " ions." Thus when a molecule of sodium 
chloride dissolves in water it divides into two parts, one, 

+ 
the sodium ion, bearing a positive charge (Na), the other, 

the chlorine ion, bearing a negative charge (CI). The 
ions have properties quite different from those of the un- 
electrified atoms. A solution of sodium chloride contains 
sodium ions, and chlorine ions, and in addition undivided 
molecules of sodium chlorides. The ions take no particular 
course, but move about in any direction, sometimes 



MOVEMENT OF IONS 5 

reuniting with others, reforming the molecule, which again 
dissociates, and so on. When, however, an electric cur- 
rent flows through the solution, the ions move in definite 
directions. Those with the positive charge (the sodium 
ions) move in the same direction as the current, and 
those with the negative charge (the chlorine ions) move 
in the opposite direction. This orderly movement of the 
ions is due to the following causes. The conductor along 



KAT 


HODE- AWODE 




■* 


1 of curretill 


+ 






_ 






/ 












^ (gg) (EDd-d-> 








/So) *-/Va (^ (SS) 
















^'^"^ ^/^* (F^ CI-* 








^^ £i^ 





Fig. I. — Passage of current through a 
solution of sodium chloride. Sodium ions 
migrating to kathode, chlorine ions to 
anode. Undivided sodium chloride mole- 
cules move in no definite direction. 

which the current enters the solution (known as the 
positive electrode, or anode) is connected to the positive 
pole of the battery, and therefore the ions with the positive 
charge are repelled from it. At the same time they are 
attracted to the conductor by which the current leaves the 
solution (the negative electrode, or kathode), because this 
conductor is connected to the negative pole at the battery. 
The ions with the negative charge make their way in a 
direction opposite to that taken by those with the positive 
charge, because they bear the opposite charge. The 



6 ESSENTIALS OF MEDICAL ELECTRICITY 

ions with the positive charge, therefore, travel in the 
same direction as the current "down-stream," while 
those with the negative charge make their way in a 
direction opposite to that of the current "up-stream." 
Those events are shown diagrammatically in Fig. i. 
Now when the ions reach the electrodes to which they 
are attracted, their electrical charges are neutraHsed and 
further chemical changes occur. These depend on the 
nature of the ion and on the material of which the 
electrodes are made. Assuming that the electrodes are 
made of a metal like platinum, which resists corrosive 
action, the positively charged sodium ion reaches the 
kathode and its electrical charge is neutralised, where- 
upon the sodium, now in the free unelectrified state, 
resumes the properties of free sodium and decomposes the 
water, forming sodium hydrate (caustic soda) and free 
hydrogen. The negatively charged chlorine ion reaches 
the anode and becomes free chlorine, some of which, in 
the nascent state, decomposes the water, forming hydro- 
chloric acid and oxygen (Fig. 2). These are not the only 
changes that take place at the poles. It will be sufficient, 
at this stage of our inquiry, to say that bodies of an 
alkaline reaction form at the negative electrode (kathode). 
If red Htmus is around this electrode it will turn blue. If 
the positive electrode (anode) is made of some metal 
that resists the action of acids, such as platinum, acids 
will be formed around this pole and can Likewise be 
demonstrated by litmus. 

The passage of the electric current through the solu- 
tion, therefore, produces two main changes. In the 
first place, the ions between the electrodes of entry and 
exit of the current migrate in definite directions, those with 
the + charge migrating towards and accumulating at the 
negative electrode, those with the - charge migrating 
towards and accumulating at the positive electrode. 
There is therefore a redistribution of ions between the 



IONS AT THE ELECTRODES 



electrodes along the path of the current. In the second 
place, new chemical bodies are formed at the electrodes. 
When a current of electricity passes through any part 
of the body, similar events take place. The tissue fluids 
contain many other salts besides sodium chloride — 
viz. carbonates, chlorides, phosphates and sulphates of 



\ 



KAT 


HODH AfV 

JK DireclioTi T 
1 oh Ci^rrent 1 


ODE 

+ 




•"S,- p) €3) jO- 

^ut ^o) (@ <^ 

OH-* ♦•H CI"* 





Fig. 2. — Passage of current through 
solution of sodium chloride. Sodium ions 
reach kathode and caustic soda and 
hydrogen (not shown) are formed. Chlorine 
ions reach anode and hydrochloric acid 
and oxygen (not shown) are formed. 
Some of the caustic soda molecules and 
hydrochloric acid molecules dissociate and 

+ _ + _ 

form ions Na and OH ; and H and CI. 

sodium, potassium, calcium, magnesium and iron, be- 
sides organic soluble salts, so that there are other ions as 
well as the sodium and chlorine ions. The two last- 
mentioned are, however, present in the largest number. 
The sodium hydrate which forms at the negative electrode 
has a caustic action on the tissue. So also has the 
hydrochloric acid which forms at the positive electrode. 
Either may be used for the destruction of tissue. This, 
the so-called electrolytic action of the current on the 



8 ESSENTIALS OF MEDICAL ELECTRICITY 

tissue, is really the chemical action of the caustic pro- 
ducts formed at the electrodes. Here we have one of the 
examples of the mode of action of electricity on the body 
by the production of chemical changes. The electrical 
current acts in this way when it is used for the destruc- 
tion of nsevi, warts, moles, etc., and the practical details 
of the method will be set forth in a later chapter. This 
method is sometimes spoken of as " surgical electrolysis " 
or " surgical ionisation." 

There is, also, in the tissues, a migration of ions be- 
tween the electrodes and a resulting redistribution. The 
conditions are more complicated in the case of the tissues 
than in the simple salt solution. There are various ions 
in the tissues and they are not in the same relative pro- 
portion or concentration in the various organs. Thus 
the tissues of the nervous system contain more potassium 
salts and phosphates, while the blood and lymph contain 
more sodium chloride and carbonate ; that is to say, in 

+ 
the former there are more K ions and PO4 ions ; in the 

+ _ _ 

latter, more Na ions and CI and CO3 ions. When the 

current traverses these tissues there must be some re- 
arrangement in the relative proportion of the various ions 
in them. When, in cases of disease, the application of 
the electric current produces a beneficial effect, the mode 
of its action may be found perhaps in the migration and 
redistribution of the ions in the diseased part, some upset 
in the balance having possibly taken place in the disease 
or possibly some new ions having been formed. It is, 
of course, very difficult in the present state of our 
knowledge to show the exact relation between ionic 
redistribution and therapeutic action. The following 
examples are suggestive as to the mode of action of the 
electric current by producing a redistribution of ions 
along the path of its flow. 
The constant current has the power to quickly abolish 



PASSAGE OF IONS THROUGH SKIN 9 

the feeling of fatigue from a heavily worked muscle. 
This was spoken of as the " refreshing " action of the 
current. What probably happens is as foUows. Fatigue 
products (perhaps sarcolactic acid or its salts) accumu- 
late in the muscle. The passage of the current through 
the muscle causes migration of these ions and many pass 
out of the muscle and into the blood vessels and lym- 
phatics of the muscle and are then at once carried away 
by the circulating fluid. 

The refreshing effect produced by passing the constant 
current through the brain (cerebral galvanisation) is 
possibly due to a similar action, the removal of fatigue 
products as a result of their migration accompanying the 
passage of the current. 

The power of the current to produce migration of ions 
can be utilised for a third purpose. If a solution con- 
taining ions is placed in contact with any part of the 
body and the current made to traverse the solution 
on its way through the body, the ions will migrate as 
previously described, so that some will pass through the 
skin into the body, and others, bearing the opposite charge, 
will pass in the opposite direction out of the body. The 
electric current can therefore be used for the purpose 
of introducing electrolytes (or, more correctly, their ions) 
into the body. A large number of drugs used in medicine 
are electrolytes. The current can therefore be used for 
the purpose of introducing drugs into the tissues, and the 
method is known as the " ionic method." 

We have, therefore, three examples of the way in 
which electricity produces therapeutic effects by means 
of the chemical changes which it can induce. These may 
be briefly re-stated : 

I. The production of new chemical bodies at the 
electrodes of entry and exit of the current into 
and from the body. These bodies have a caustic 
action, and are used for the destruction of diseased 



10 ESSENTIALS OF MEDICAL ELECTRICITY 

and unnecessary tissue. The process is known as 
" surgical ionisation." 

2. The rearrangement of ions along the path of the 

current through the tissues. 

3. The introduction of new ions from without. The 

process is called " medical ionisation," and the 
method is known as the " ionic " method. 

The changes mentioned under 2 and 3 are on the 
border-line between chemical and physical ; they may be 
called physico-chemical. 

While the current is passing through the body it 
stimulates the excitable tissues, as indicated by the 
subjective sensations produced, such as pain, the feeling 
of burning and pins and needles. These sensations are in 
all probability the result of the movement of ions through 
the sensory nerves and end-organs. If the current flows 
constantly in the same direction and with strength un- 
varied, no muscular contraction is noticed. The steady 
movement of the ions stimulates sensory nerves, but not 
motor nerves or voluntary muscle. If, however, the 
movement of the ions is suddenly stopped by switching 
off the current, the muscles give a single twitch at the 
moment the current is interrupted. A single twitch is 
also noticed at the moment when the current is switched 
on again, and the movement of the ions again suddenly 
started. An abrupt start of ionic movement or cessation 
of movement is therefore necessary if voluntary muscle 
is to be stimulated to contract. The former happens to 
be a more effective stimulus than the latter, so that the 
twitch occurring at the moment when the current is 
switched on (the so-called " closure contraction ") is 
larger than that occurring at the moment when the 
current is switched oft (the "opening contraction"). 
Other tissues, besides muscle and nerve, are in all prob- 
ability stimulated, and the beneficial action of electricity 
in the treatment of certain conditions (of which paralysis 



IONIC OSCILLATION ii 

may be mentioned as one) is not to be attributed to any 
mysterious or vital action of the electricity, but rather 
to the stimulation of the tissues produced by the ionic 
movement that is a necessary accompaniment of the 
passage of the electric current. 

Just as a sudden movement in the same direction 
or sudden cessation of movement of ions will cause a 
voluntary muscle to contract, so will a sudden reversal 
of their movement. If the reversal is slow, the current 
slowly sinking to zero and then rising to its maximum with 
equal slowness, but in the opposite direction, there will 
be no contraction of muscle, but a sensation of smarting 
and pricking will be perceived, because the slow to-and-fro 
movement of the ions acts as a stimulus to sensory 
nerves, but not to voluntary muscle or motor nerves. If 
the reversal of the current becomes more frequent, the 
ionic oscillation will become sufficiently frequent to 
stimulate motor nerves and muscle, and contraction will 
occur. With a still greater frequency of current reversal 
and ionic oscillation aU sensation will disappear, except 
that due to the contraction of the muscles. Finally, 
when the frequency of the current reversal becomes 
extremely high — a million or more reversals taking place 
each second (this is the so-called " high-frequency " 
current) — ^there will be no contraction of muscles and 
no stimulation of nerves, and there will be no chemical 
change of any kind. 

This inability of the high-frequency current to produce 
the physiological phenomena that are brought about by 
the constant current or the current that oscillates with a 
lower frequency had, for many years, received no satis- 
factory or intelligible explanation. But if the pheno- 
menon is considered in the light of the behaviour of the 
ions that accompanies the flow of the current, and the 
electrical stimulus regarded as a sudden ionic movement, 
it receives a satisfactory explanation. If the current 



12 ESSENTIALS OF MEDICAL ELECTRICITY 

travels to and fro with a frequency of a million or more 
per second, the ions are unable to keep pace with it : 
they remain stationary, and there is no ionic movement. 
During the millionth part of a second for which the 
current is flowing in any one direction before it reverses, 
the ions have been unable to move, or, at any rate, to 
move sufficiently to bring about a stimulation of excit- 
able tissue. Now that it is possible to pass an electric 
current through the body without stimulating the excit- 
able tissue, and without producing chemical change, we 
are able to utilise electricity for the production of heat 
within the body. Since the high-frequency current does 
not stimulate the excitable tissues, it may be sent 
through the body in strength far greater than that per- 
missible for constant or low-frequency current, and it 
will then develop heat on its path through the tissues as 
it overcomes their resistance. The constant current or 
low-frequency current are unable to act in a similar way, 
because they would produce violent muscular contrac- 
tion and unbearable pain long before they reached a 
strength sufficient to develop heat. The heat that is 
generated by the high-frequency current is developed on 
the path along which it flows, so that the deep-lying 
tissues are heated as well as the superficial. The raising 
of the temperature of the deep as well as the superficial 
tissues is known as " diathermy." It forms an impor- 
tant branch of medical electricity, and is described in 
Chapter XII. 

High-frequency currents were used in medicine for 
many years without a clear knowledge of the way in 
which they produced their physiological and therapeutic 
effects. The recognition that these results were due to 
the development of heat within the tissues and organs 
showed that the high-frequency apparatus then in use 
for medical purposes was not suitable for the production 
of much heat. The modern diathermy apparatus has 



ACTION OF STATIC BREEZE 13 

since been evolved with this end in view — viz. the 
generation of the largest quantity of heat. 

The development of heat within the tissues by the 
high-frequency current is an example of the other mode 
of action of electricity on the body — viz. by the pro- 
duction of physical effects. The physical effect is, in 
this case, the development of heat. In the case of 
the constant current and the currents of low-frequency 
oscillation, the effects are chemical or physico- 
chemical, and are brought about through the agency 
of ionic movement ; in the case of the high-frequency 
current the effects are thermal and the ions are not 
moved. 

Electricity can produce chemical and thermal effects in 
another way, quite different from that already described. 
The static breeze and high-frequency effluve will illus- 
trate this. These forms of electrical application will be 
described later, but here it may be said that electricity 
at a very high potential is applied, so that if an air-gap 
is inserted between the electrode and the patient's body, 
the electricity, if directed from a pointed electrode, is 
able to bridge the gap in the form of a brush of nearly 
silent violet sparks, scarcely visible except in the dark. 
The application of this brush to the skin strongly 
stimulates the latter. The stimulation is due most 
probably to the heating of minute points of skin. 
Erythema is produced and even urticaria, if the applica- 
tion is strong. We are able, in one instance at any rate, 
to trace the physical, physiological and therapeutic re- 
sults of the appHcation of electricity. A patient suffers 
from headache as the result of low blood pressure. The 
application of the static breeze induces an er3^hema by 
the heating of minute points of the skin, and, as a 
physiological result of peripheral stimulation of the 
sensory nerves, there is a reflex rise of blood pressure 
and the headache disappears. 



14 ESSENTIALS OF MEDICAL ELECTRICITY 

The passage of the brush discharge through the 
atmospheric gases causes the formation of ozone and 
nitrous and nitric acid. It is probable that these chemical 
products play a part, by virtue of their germicidal action, 
particularly in the treatment of some skin affections and 
infected ulcers. 

The application of sparks from a static machine wUl 
frequently reheve pain in the region of muscles and 
fasciae — e.g. the Imnbar region — and the relief is some- 
times instantaneous. The mode of action of electricity in 
such cases is, most probably, mechanical. The sudden 
powerful muscular wrench that accompanies the passage 
of a long spark breaks down adhesions. The static wave 
current also produces rhythmic muscular twitches, but 
less violent and more agreeable than those produced by 
the sparks. In bringing about relief, as it often does, in 
certain cases of chronic inflammation and congestion {e.g. 
traumatic synovitis, chronic neuritis, etc.), electricity, in 
the form of the static wave current, produces its results 
by physical (mechanical) methods. In applying the 
static wave current (the details wiU be given later) 
the body is alternately charged and discharged, the 
electricity suddenly escaping, during discharge, by 
way of an electrode placed in contact with the part 
requiring treatment. The therapeutic results are to 
be attributed, not directly to the electricity, but 
rather to its power of producing physical (mechanical) 
changes, the rh5rthmic twitching of the muscles 
inducing local acceleration of the circulation and 
mechanical removal of the effusion and loosening of 
adhesions. 

It is not pretended that the account given in this 
chapter of the mode of action of electricity will explain, 
in every case, the way in which disease responds to 
electrical treatment. But if we look upon the cure or 
relief of disease by electrical methods as due, not directly 



ACTION OF STATIC BREEZE 15 

to the electricity itself, but rather to known chemical or 
physical changes that it produces, we are better able to 
judge whether electrical treatment is suitable for a case, 
and foresee the results that may be expected from its 
application. 



CHAPTER II 

THE CONSTANT CURRENT AND ITS MODIFICATIONS 

The various methods of applying electricity for the 
treatment of disease are, to all outward appearance, very 
dissimilar, as will be apparent to one who visits a modern 
electrical clinic. Yet in the greater number of cases an 
electrical current is applied, modified, in one way or 
another, and producing different physical and physio- 
logical effects. Each current may be derived, directly 
or iadirectly, from one source — ^that is, the constant 
current. In this chapter it is proposed to describe the 
various modifications of the electrical current, taking 
the constant current as the starting-point. 

The Constant Current. — ^This current is so called 
because its strength does not vary and its direction of flow 
does not change. It is sometimes called the " continuous 
current," sometimes the " galvanic current." The 
constant current supplied on the mains in certain 
districts is generally called the " direct current," or, for 
short, DC. 

The constant current may be obtained by chemical 
action, such, for example, as that which takes place in a 
battery cell or accumulator, or by mechanical action, as 
in the revolution of the armature of a dynamo. 

This current can be accurately measured. When 
it is to be used for medical purposes we should know 
its voltage and its amperage. These are measured 
by the voltmeter and amperemeter respectively. The 
amperage expresses the strength of the current, or, more 
accurately, the quantity of electricity passing along the 

i6 



SIMPLE INTERRUPTED CURRENT 17 

circuit ; and the voltage is a measure of the pressure or 
force at which the electricity is impelled onwards. 

A graphic representation of the constant current would 
be a horizontal straight Line parallel to a base-line repre- 
senting zero, and above it or below it according to the 
direction of the current, while the distance above it or 
below it would indicate either its pressure or its strength. 

For medical purposes this is probably the most impor- 
tant and generally useful form of electrical current we 
have. 

Simple Interrupted Current. — ^This current flows 
always in the same direction, but the flow is intermittent, 



H 

Fig. 3. — Graphic representation of simple inter- 
rupted current. The periods of current-flow and periods 
of no-flow are, here, of the same duration, 

not continuous. There are alternate periods of flow and 
no-flow. During each period of flow the current strength 
is constant. At the end of this period the flow ceases 
suddenly, and the period of no-flow follows. At the end of 
the latter period the flow is suddenly resumed. A graphic 
record of a simple intermittent current is shown in 
Fig. 3. BC represents a period of flow, DE a succeeding 
period of no-flow. CD represents the sudden cessation 
of the current, EF its sudden resumption. The height 
of the hne above the base-line would be proportioned to 
voltage or amperage ; the distance along the base-line 
would indicate time intervals. 

Such interruptions of the current can be produced by 
alternately making and breaking the circuit along which 
the current flows. This can be effected by various 
mechanical devices. A simple make -and -break key can 



i8 ESSENTIALS OF MEDICAL ELECTRICITY 



be introduced into the circuit and operated by hand. A 
metronome can be adapted (Fig. 4), so as to produce 
regular and even interruptions. The swinging arm bears 
a horizontal wire, to each end of which is fixed a short 
vertical wire. Another vertical wire of equal length is 
fixed to the centre of the horizontal piece. When the 
arm of the metronome swings to and fro, the horizontal 
wire moves with it, and the vertical wires at the extremity 

of the latter rise and 
fall. Three small cups 
of mercury are fitted to 
the metronome, and so 
arranged that as the 
vertical wires fall and 
rise they dip into and 
rise out of the mercury 
in the cups. The central 
vertical wire does not 
rise or fall, but stays 
permanently immersed. 
The vertical wires that 
dip into the mercury 
should be made of silver. 
A terminal is connected 
to each cup. To use 
the metronome as a current interrupter, one end 
of the wire conveying the current is attached to the 
central cup, the other end to one of the end cups. When 
the wire rises out of the mercury the current is inter- 
rupted. The number of interruptions per minute will 
depend upon the rate of swing of the metronome. The 
time the current flows between each interruption depends 
upon the rate of swing of the metronome and the depth 
to which the wire dips into the mercury. The metronome 
can be used to interrupt two currents alternately. Of 
the wires conducting the second current one is connected 




Fig. 4. — Metronome Interrupter 



MECHANICAL CURRENT INTERRUPTER 19 




to the other end cup, the other wire to the central 
cup. 

The metronome interrupter may be used when regular 
interruptions of a current are desired without accurate 
measure of their duration. It is used in the process of 
muscle-testing by the condenser method, and in some 
forms of electrical , 

treatment. ^ ' 

Another device for 
procuring simple 
interruption of the 
constant current is 
Leduc's mechanical 
interrupter. By 
means of this instru- 
ment the current 
may be interrupted 
as frequently as de- i ^* — c 

sired, and the periods Fig. 5.— Plan of commulator of Leduc. 

of flow and of in- When the current flows Irom the fixed 
brush-holder AB to the movable brush- 
terruption may be holder in the position CD, the period of 
varied and accurately current-flow is the longest and of no-flow 

1 the shortest. 

measured. When the movable brush-holder is in 

Leduc's Mechanical the position C'D', the period of current- 
Current Interrupter, fj^^^^' ^^^ '^""'^^'^ ^"^ ""^ "^-^^"^ ^^^ 
— ^The essential part 

of the apparatus is a disc of insulating material 
mounted on the axle of a small motor and rotating with 
it (Fig- 5). Four metal strips are secured on the 
circumference, each being of equal length. They are 
placed symmetrically around the circumference. There 
is a small interval between consecutive strips. Dia- 
metrically opposite strips are in metallic connection with 
each other. Two contact brushes press against the 
circumference of the wheel, one being fixed, the other 
being movable through an arc of 90°, so that it may 



20 ESSENTIALS OF MEDICAL ELECTRICITY 

touch the circumference at a point diametrically opposite 
the fixed brush, or at any point nearer, but not closer 
than one quarter of the circumference. The current can 
pass from one brush to the other, so long as the brushes 
are in contact with diametrically opposite pairs of discs. 
When the brushes are in the position shown in Fig. 5 
(continuous lines), the current can flow from one strip 
to that opposite and continue to flow, when the strips 
are revolving, for the longest time possible. But when 




Fi(}. 6. — Leduc's Mechanical Interrupter 

the movable brush has been moved round through 90° 
the current can flow only for the shortest time. In the 
first position the current flows for the longest time 
and the period of no-flow is the shortest. In the second 
position the period of flow is the shortest and that of no- 
flow is the longest. Intermediate positions of the brush 
give other periods of flow and no-flow. Increase of the 
length of the time of current-flow shortens the period of 
no-flow, and vice versa. The number of interruptions 
of the current depends upon the speed of revolution of 
the disc. The number of revolutions per second can 



SIMPLE ALTERNATING CURRENT 21 

be indicated by a speed indicator. Increase of the speed 
of the interrupter will shorten the periods both of flow 
and no-flow. 

By means of this current interrupter it is possible to 
vary the number of interruptions and measure the 
duration of the period of flow of the current, and the 
period of no-flow. The interrupter is shown in Fig. 6. 

Simple Alternating Current. — ^This current differs 
from the simple interrupted current in that it flows, dur- 
ing successive periods, in opposite directions. A graphic 



B yi 



■ 


f 




c 


C 


D 


A 


D' 


£ 


F 


B 



B 



T 



Fig. 7.— Ruhmkorffs Commutator 

record of such a current is shown in Fig. 8. Between 
the successive periods of current -flow there are periods 
of rest, so that the current is intermittent as well as 
alternating. The simple alternating current may be 
obtained from the constant current by means of the 
device known as a Ruhmkorff's commutator. This is 
often fitted to galvanic batteries and induction coils for 
the purpose of reversing the direction of the current when 
desired. If it is attached to the revolving axle of a 
motor, the direction is periodically reversed at a rate 
depending on the speed of revolution of the motor, so 
that a simple alternating current is provided. 
The Ruhmkorff commutator (Fig. 7) consists of a 



22 ESSENTIALS OF MEDICAL ELECTRICITY 

cylinder of hard rubber, A , mounted on a spindle, B so as 
to revolve freely. On each end of the cylinder are fixed 
metal bands, C and D, and from one side of each band the 
metal extends for about two-thirds the length of the 
cylinder, in the form of cheeks C and D' , but not so far 
as to come into contact with the band at the opposite 
end. The cheeks C and D' are usually made to embrace 
about one-fourth the circumference of the cylinder and 
are so fixed as to be exactly opposite each other. Four 
metal springs are now required. A pair, EE, is mounted 
one at each end of the cylinder, so as to press on the metal 



Fig. 8. — Graphic representation of a simple interrupted and 
alternating current. The periods of current-flow are here equal 
to the periods of no-flow. 

bands, C and D. The other two, FF, are mounted on 
opposite sides of the cylinder at its middle, so as to touch 
the cheeks, C and D' , as the cylinder is revolved. The 
wires from the battery or other source of constant current 
are connected to the springs, EE, and the current led off 
by wires joined to the springs, FF. It will be seen that 
the direction of flow tDf a current in a wire joining the 
springs FF will be reversed each time the cylinder is 
rotated through half a revolution, and if the rotation is 
kept up the wire wiU be traversed by a simple alternating 
current. Such a current is graphically represented in 
Fig. 8. When the space between the metal cheeks is 
equal to the width of the cheeks, each period of flow of 
the current is followed by a period of rest of equal 



SINUSOIDAL CURRENT 23 

duration. This period of rest can be increased or 
diminished by varying the width of the metal cheeks. A 
commutator for practical use is made so as to give from 
four to eight or more cycles per revolution, and so obviate 
the necessity for driving it at very high speed. The 
principle of its construction is the same as the one here 
described. 

Sinusoidal Current.— This current is supplied on the 
main in certain districts under the name " alternating 




Fig. 9. — Graphic representation of a sinusoidal current — 
one complete phase. 

current." It is a very useful current for many medical 
purposes. It can be taken direct from the main where 
the supply is an alternating current ; where the supply 
is a constant (direct) current, the latter can be readily 
converted into a sinusoidal current by a motor trans- 
former. To understand the way in which a sinusoidal 
alternating current is generated requires some know- 
ledge of the mechanism of dynamos. This is briefly 
described on page 289. The sinusoidal current is an 
alternating current, but it differs from the simple alter- 
nating current just described, in that its rise from zero to 



24 ESSENTIALS OF MEDICAL ELECTRICITY 

maximum and its fall from maximum to zero is gradual, 
not sudden. Further, on reaching zero, there is no 
period of intermission, but a second rise to maximum 
and fall to zero in the opposite direction. A graphic 
representation of a sinusoidal current is shown in Fig. 9. 
From A to B the current is rising to its maximum ; from 
B to C it is falling to zero ; from C to D it is rising to a 
maximum again, but the current is flowing in an opposite 
direction ; from D to E it is falling again to zero. 
ABCDE represents a complete cycle or phase. The 




Fig. 10 



" periodicity " of the current refers to the number of 
these complete cycles per second. If the current has a 
periodicity of 100, there are 100 of these cycles each 
second. From A to E the time interval would be yJo^h 
second ; from A to C g-J^th second. The height of the 
curve above the base-line at any spot is proportioned to 
the voltage or amperage. 

The alternating current supplied on the main is gener- 
ated at the power station by a d3mamo. When the 
direct current is supplied on the mains, or when it can be 
obtained from a battery of accumulators, a sinusoidal 
current may be readily obtained by means of a motor 
transformer. Makers of electro-medical apparatus now 



SLOW SINUSOIDAL CURRENT 25 

put on the market different patterns of so-caUed 
"universal" apparatus, sold under the trade names of 
" Pantostat," "Multostat," '' Polystat," etc., and these 
convert constant into alternating sinusoidal currents. 
Such instruments are now largely used, and one pattern 
is illustrated in Fig. 10. 

Slow Sinusoidal Currents. — ^The alternating cur- 
rents on the mains have a periodicity not higher than 
100 and not lower than 25. If there are fewer than 25 
complete cycles per second {i.e. 50 reversals per second), 
lamps that are illuminated by such a current will not 
give a steady light. Sinusoidal currents of a lower 
periodicity are sometimes used in medicine, and Dr 
Reginald Morton has recommended the use of currents 
with a periodicity as low as 1-7 — that is, in each second 
there are 1*7 cycles. The duration of each cycle would 
then be very nearly 0-6 seconds. 

A slow sinusoidal current may be obtained from a 
motor transformer that is made to revolve slowly. This 
method is, however, very wasteful of current. A better 
method is to use a rhythmic reverser, such as that of 
Ewing. This is shown in plan in Fig. 11. The following 
description is taken from Dr Lewis Jones : — 

" An insulating drum of ebonite is revolved in a glass 
cylindrical vessel of water which it nearly fills. There 
are metallic armatures, CD, inside the vessel at opposite 
ends of a diameter. Corresponding armatures, A and B, 
are fixed to the ebonite drum. If a difference of potential 
be maintained between C and D, as indicated by the signs 
+ and - , there will be a flow of current from A to B 
through a conducting circuit joining these points, when 
the drum is in the position shown in the figure, and if the 
drum is turned round through 180° there will be a flow 
from jB to ^ as the positions of A and B relative to the 
armatures C and D will have been reversed. Thus by 



26 ESSENTIALS OF MEDICAL ELECTRICITY 

rotating the ebonite drum a sinusoidal current will be 
set up in the circuit A B. It will reach its maximum 
when the armatures A and B are close to C and D and 
will be at zero when they occupy the positions at right 
angles to this. To utilise the current in the circuit A B 
it must be collected by means of rings and brushes very 




Fig. II. — Plan of Ewing's Rhythmic Reverser 

much in the way used with an alternating current 
dynamo." 

Faradic Current. — This is the current that is obtained 
from the induction coil. The induction coil does not 
actually generate the current, but transforms the current 
of the battery attached to it. The latter is a constant 
current of low voltage. The coil transforms it into one 
of much higher voltage with corresponding diminution 
of amperage, and at the same time makes it intermittent 
and alternating. A graphic record of such a current is 



INDUCTION COIL 27 

shown in Fig. 13. It may seem unnecessary to the 
student to consider the matter of the output of induction 
coils, but the subject is important, as a clear understand- 
ing of it will show why it is that some medical coils 
produce painful and disagreeable results when used for 
treatment, and will show why the induction coil is not 
the most suitable instrument to employ when accurate 
results are desired in the investigation of the reactions 
of muscle and the physiological response of excitable 
tissues. 

'" Before describing the meaning of the curve shown in 
Fig. 13 an account of the induction coil will first be 
given. 

The induction coil is probably the best known electrical 
device in use by medical men and others. It is very 
inexpensive, especially in its simplest forms, and for 
stimulating living tissues it may be quite efficient. 
From the fact that it lends itself very readily to great 
variation in constructional detail, without seriously 
interfering with its working qualities, few instruments 
have been subjected to such extensive modifications — 
and though much ingenuity has been expended on it, it 
is doubtful if any substantial improvement has resulted. 

Notwithstanding its complicated appearance, especi- 
ally to the uninitiated, the induction coil is really a very 
simple appliance. Its essential parts^are Jshown in 
Fig. 12. 

A is an iron core — ^usually made up of a bundle of soft 
iron wires — ^around which is wound a comparatively few 
turns of fairly coarse wire : this is the primary coil. In 
all cases the wire used for winding coils is covered with 
silk or cotton for purposes of insulation. Opposite one 
end of the core is an iron block, B, which is secured to the 
end of a metal spring, C. A screw, D, is mounted so that 
its point comes opposite about the middle of the metal 
spring. The end of the screw and that part of the spring 



28 ESSENTIALS OF MEDICAL ELECTRICITY 

with which it comes into contact are both faced with 
platinum. One end of the primary coil is connected with 
one pole of the battery, E — ^the other is connected to the 
spring, C. The other pole of the battery is connected to 
the screw, D. 

Around the primary coil, but quite disconnected from 
it, is another coil of much finer wire and Wound in very 
many more turns. This is the secondary coil. It is not 
shown in Fig. 12. 

The secondary coil generally consists of a large number 
of turns of fine wire. It is not directly connected in any 




Fig. 12 

way with the primary, but is wound on a bobbin, the 
hole through the centre of which is large enough to slide 
over the completed primary coil. By so doing the 
secondary is brought more or less into the magnetic field 
of the primary, and the electro-motive forces in it thereby 
adjusted. The secondary has from five to fifteen times 
the number of turns of the primary, for which it is made. 
The average proportion of primary turns to secondary 
turns is i : 10. 

The course of the current can be easily traced from the 
battery to the primary coil, from this to the spring, C, 
thence through the platinum contacts to the screw, D, 
and so back to the battery. The current passing round 
the primary coil, the latter becomes, with the iron core, 



FARADIC CURRENT 29 

an electro-magnet. It thus attracts the iron block, B, 
and in drawing the latter towards itself pulls the spring, 
C, away from the point of the screw, D. Immediately 
this happens the circuit is broken and the flow of current 
from the battery ceases. The core thus loses its magnet- 
ism, and the iron block no longer attracted, the spring, C, 
by its own elasticity flies back until it is stopped by the 
point of the screw, D. The circuit is thus again closed 
and the above-mentioned changes are repeated. 

We may now consider the events that take place in 
the primary and secondary coils. Since the vibrating 
spring continually makes and breaks the primary circuit, 
the current flowing in this circuit (the primary current) 
is interrupted or intermittent. Further, at " make " and 
also at "break," an extra current is induced, not only in 
the primary circuit (the primary induced current), but 
also in the secondary circuit (the secondary induced 
current). These induced currents are of momentary 
duration. They may be taken in order : 

1. At " Mcle" of the Pir.mary Circuit. — ^The battery 
current flows around this circuit, but at the same time a 
new current of momentary duration is induced in the same 
circuit ,and it flows (as mentioned in Chapter XV., p. 287, 
under Self-induction) in the opposite direction, impeding 
it and slowing its rate of rise to its maximum. This is 
shown in Fig. 13, a to h. It indicates the slow rise 
of the current in the primary to maximum. As a result 
of this impeded rise, the current that it induces in the 
secondary coil is of correspondingly long duration and 
does not reach so high a voltage (see Fig. 13, curve from 

. A to B). 

2. At" Break " of the Primary Circuit. — ^At the moment 
the primary circuit is interrupted the battery current 
ceases to flow, and at the same time an extra current is 
induced in the same circuit ; it flows in the same direction 
as the battery cturent, and therefore the induced current 



30 ESSENTIALS OF MEDICAL ELECTRICITY 

is not impeded, but increased, and the cessation of the 
current in the primary circuit is abrupt (Fig. 13, h to c). 
The abrupt cessation of the current in the primary in- 
duces in the secondary a current of brief duration, briefer 
than that of the current induced in the same coil at 
" make " and one at higher voltage (Fig. 13, BCD). 

It is evident, then, that the faradic current is highly 
complex. Further than this, the graphic record of the 

A BCD -Induced current in. secondary/ coll 
AB- Make Curreat BCD- Break Current 

(tcusfinj 0-0037 ict.) 




odbc - Exciting current in primary coil 
ab- Make Current be -Break Curreut 

Fig. 13. — Graphic record of the primary and secondary 
currents of an induction coil. 

[Adapted, by permission, from Jones' Medical Electricity. 
6th Edition. H. K. Lewis & Co. Ltd., London. 

output of induction coils varies greatly in coils of differ- 
ent design. The output depends on the length of wire in 
the primary and secondary coils, the presence or absence 
of an iron core, the design of the vibrating spring, the 
method of regulating the output, etc. The output may^ 
also vary in the same coil from time to time, according to 
the adjustment of the hammer, etc. We may therefore 
speak, not of a faradic current, but of varieties of faradic 
current. Any type of medical coil will give a current 
that will stimulate the tissues, but few will give a current 



RECORD OF FARADIC CURRENT 31 

that will stimulate them painlessly. The question of the 
output of induction coils is a subject of much importance, 
both from the point of view of electrical treatment, and 
also the testing of the reactions of muscle and nerve. 
The first of these may be considered here ; the second 
will receive attention in the chapter on the testing of 
electrical reactions. 

Motor nerves and muscles will respond to currents of 
very brief duration. Sensory nerves, however, require 
currents of longer duration. The current that is pro- 
vided by an induction coil should last, during each period 

ABCD - Induced correntm secondary coil 
AB - Make Current BCD -Break Ci;rrent 




Fig. 14. — Graphic record of the secondary current from a 
well-designed coil. 

[Adapted, by permission, from Jones' Medical Electricity. 
6th Edition. H. K. Lewis & Co. Ltd., London. 

of flow, the briefest possible time, so that muscles and 
motor nerves may be stimulated, and not the sensory 
nerves. A coil giving a record like that shown in Fig. 13 
would produce painful contractions of muscle, because the 
secondary current flows for periods that are long enough 
to stimulate sensory nerves. Many other coils give 
currents that produce the same effect. A coil that is 
most suitable for medical treatment is one that produces 
the most vigorous contractions without disagreeable 
sensation. This requirement will be fulfilled if the in- 
duced current in the secondary at " break " is of the 



32 ESSENTIALS OF MEDICAL ELECTRICITY 

shortest possible duration, and that at " make " being of 
insufficient strength to cause skin sensation or muscular 
contraction. A coil giving a graphic record like that shown 
in Fig.. 14 would give the most agreeable and painless 
contraction of the muscles. The records in Figs. 13 and 
14 are on the same scale. The record of the secondary- 
current is given in Fig. 14 (not of the primary), and it will 
be seen that the duration of the current at " break " BCD 
is very brief (yoVxr second) ; that at " make " being of 




Fig. 15 

insufficient intensity to cause perceptible stimulation. 
An electrical stimulus or impulse is produced each time 
the current at " break " flows. The number of these im- 
pulses per second depends on the rate of vibration of the 
spring. In the record shown the number was nearly 100 
per second. Such a coil (Fig. 15) was designed by Lewis 
Jones, and the oscillographic record shown in Fig. 14 was 
obtained from one of this design. It is a valuable coil for 
use in medical practice, as the current wiU evoke strong 
muscular contractions without disagreeable sensation. 
It is enclosed in a case containing a dry cell and is portable. 
The primary circuit is completed and interrupted by a 
spring vibrating in a horizontal plane and actuated by 
the iron core within the primary coil. This core is not 



REQUIREMENT OF INDUCTION COILS 33 

movable. The secondary coil can be made to slide as a 
sledge over the primary coil. The current that is applied 
to the patient is taken from the secondary coil and is 
regulated by sliding the secondary over the primary. 
Three binding screws are connected to the secondary 
winding. From two of these the current from only one- 
third of the length of the secondary wire is taken. This 




Fig. 16. — Sledge Coil 



current is of lower voltage and is the most suitable when 
it is to be applied to the body through the damp skin by 
way of moistened pads, so as to lower the resistance. 
From another pair of binding screws the current from 
the whole length of the secondary is taken. The current 
is of higher voltage and is the one to be chosen when it is 
to be led through the higher resistance of dry skin. 

There are many other designs of medical coils on the 
market. The requirement of a coil that is to be used 
for medical purposes is the power to produce strong con- 
traction without pain. The readiest test is the sensation 
produced on one's own cheek, applying the current 



34 ESSENTIALS OF MEDICAL ELECTRICITY 

through damp pads. The most accurate test is furnished 
by the graphic record given by the oscillograph. 

Induction coils fitted with separate electro-magnets 
for working the vibrating spring produce irregular and 
uneven impulses and disagreeable sensory stimulation. 

Many types of coil are made. Some of them are pro- 
vided with an extra pair of terminals, so that either the 
primary or the secondary induced current can be applied 
to the patient. In Fig. 12, ^represents the handles that 
lead the primary induced current to the patient. The 
primary current is regulated by sliding a brass tube 
over the iron core. Other coils have an arrangement 
in the form of a bent wire and a sliding ball (Fig. 16) 
fixed to the hammer, for the purpose of regulating tha 
rate of vibration of the latter. 

The question of the output of induction coils has been 
considered at length, because this form of electrical in- 
strument is so widely used for so many medical purposes, 
and is not always of correct design. The best test of 
a coil for medical and physiological purposes is furnished 
by an oscillographic record. 

The high-frequency and diathermy currents and the 
static wave and static induced currents wiU be described 
later, in the chapters dealing with these forms of electrical 
appHcation. 



CHAPTER III 

SOURCES OF ELECTRICAL SUPPLY 

When it has been decided to make use of electricity 
for the treatment of disease, the first practical question 
which arises is that of supply. There are different 
sources of supply and the selection will depend on what 
is available and most convenient. In almost all the 
applications of electricity for medical purposes, a current 
of one or another kind is used, and the current which 
constitutes the source of supply may require modifica- 
tion according as it is used either for direct application 
to the body or for the generation of other kinds of 
currents, or for other purposes. There are the following 
sources of supply : 

1. The Street Mains. 

2. Cells and Accumulators. 

3. Dynamo and Driving Plant (private installation). 
Each of these has its advantages and limitations. These 
will be set forth in the present chapter, together with 
the methods of modifying them so as to render them 
suitable for different purposes. For the generation of 
static electricity an influence machine is required, with 
an electric motor or gas or oil engine to drive it. 

Current from the Main — ^The town supply that is 
distributed along the street mains and taken into many 
of the houses is the most convenient and economical 
source. The current is in some towns and districts a 
direct current (DC.) — i.e. its direction is unvarying. In 
others it is an alternating current (AC.) — that is, its 
direction is periodically reversing. The voltage at 

35 



36 ESSENTIALS OF MEDICAL ELECTRICITY 

which it is supplied is not always the same in different 
towns ; in some it may be lOO, in others 200 or 250. 
And in the case of the alternating current the frequency 
of the alternation differs in different towns. It is there- 
fore necessary to find out with regard to the town 
current whether it is a direct or an alternating current, 
the voltage at which it is suppUed, and the frequency of 



Correut Jvom tnaia 



Cffpcnt jicvn nicnn 




Fotient 



B 



Fig. 17. — Current derived from main with resistance in 
shunt (A), in series (B). 

the alternation when the town supply is an alternating 
current. These particulars are published each year in 
the January number of The Electrician, 

The Use of the Direct Current from the Main. — 

The direct current is the most generally useful for medical 
work. The voltage at which it is suppUed is in some dis- 
tricts 100 ; in others it may be as high as 250. The current 
that is taken to the lamp-holders and plugs has a strength 



SHUNT RESISTANCE 



37 



up to 5 amperes. Such a current has too high a voltage 
and amperage for direct appHcation to the body, and 
it must therefore be reduced. The simplest and least 
expensive method of reducing its voltage and amperage 
is to insert a sufficiently high resistance. This resistance 
could be inserted in series with the patient, in which 
case the patient and the resistance would both be in 
the same circuit, and the current would traverse each in 
turn (Fig. 17, B). Such an arrangement is unsatis- 
factory, and the usual plan is to arrange the resistance 




Plan of Shunt Resistance 



in shunt. In this case the patient and the resistance 
are in separate circuits, and the current traverses each 
simultaneously (Fig. 17, A), the amount passing through 
each depending on their relative resistances. The re- 
sistance in the patient's circuit can be varied by includ- 
ing in the same circuit a varying length of the shunt 
resistance. This can be effected by connecting one of 
the wires leading to the patient — ^not to the end of the 
shunt resistance, but to a point a varying distance along 
it. With such an arrangement, part of the shunt 
resistance is in series witfi the patient. 

Fig. 18 is a diagram showing the necessary arrange- 



38 ESSENTIALS OF MEDICAL ELECTRICITY 

ment. The fine wire coil, from A to B, and the lamp at 
B constitute the shunt resistance. If we trace out the 
connections we see that the current comes in from the 
main at the positive terminal to the switch. When the 
switch is turned on the current flows through the fine 
resistance wire from A to B, then through a lamp and 
safety fuse to the negative terminal of the main. It 
also flows, when the patient is connected, along part of 
the length of the fine wire to the slider, C (this can be 
moved to the right or to the left), then through the 
galvanometer and through the patient back to the 
other circuit at B. The strength of current that passes 
along these two circuits will depend upon their relative 
resistances. The resistance of the circuit containing the 
fine wire and the lamp is constant, that of the other 
circuit containing the patient will depend upon the 
length of resistance wire between A and the slider, C. 

On the + side of the connection with the main (Fig. 
i8) the voltage is at the maximum supplied on the main ; 
on the - side of the connection it has fallen to zero. 
The fall takes place gradually and evenly along the 
resistance from A to B. A further fall takes place in 
the lamp at B, and zero is reached on the - side of the 
fuse. From A to B the fall is even — there is a " slope 
of potential," as it is called. 

If we take a sensitive volt-meter and connect one 
terminal to B, and having attached a piece of wire to the 
other terminal of the volt-meter, draw the free end of 
this wire across the turns of the resistance from B to A, 
we will find that we can get any voltage we desire from 
zero up to the highest given by the instrument — this 
will be from 50 to 80, depending on the resistance of the 
lamp at B. 

Now it will be seen on reference to Fig. 18 that the 
patient is connected in the same way as the volt-meter. 
One of the terminals that lead to the patient is connected 



SHUNT RESISTANCE 



39 



to B, the other is connected with the sUder, C, which 
can be moved along the resistance coil, AB, and in con- 
tact with it. This slider, C, is mounted on a metal rod 
that is placed parallel to the resistance coil and at such 
a distance from it that its springs are always in contact 
with it. The voltage 
of the current that 
passes to the patient 
can therefore be 
varied between zero 
and maximum by 
sliding, C, along the 
resistance coil from 
B to A. When the 
slider is at B, the 
terminals that lead 
to the patient will be 
in connection with 
the same region of 
the resistance coil, 
and there will be no 
d ifference of potential 
between the termi- 
nals, and no current 
will pass to the 
patient. On moving 
the slider farther and 
farther away from B 
towards A, the vol- 




FiG. 19. — Shunt Resistance 



tage between the terminals will rise higher and higher, 
and more and more current will pass to the patient. 
Its value is indicated by the milliampere-meter placed 
in the same circuit with the patient. 

Fig. 19 is an illustration of the actual apparatus the 
plan of which has been described. The various parts 
are mounted on a board that can be fixed permanently 



40 ESSENTIALS OF MEDICAL ELECTRICITY 

to the wall. At the top are mounted the lamp, switch 
and safety fuse. Underneath is the resistance coil. In 
front of this is the slider which can be moved from side 
to side over its surface. The scale below the resistance 
coil serves to indicate the position to which the sUder 
has been moved on any occasion. At the bottom of the 




Fig. 20 

board are two terminals to which will be fixed the cables 
that lead the current to the patient . A milHampere-meter 
IS not attached to this board. 

Fig. 20 shows a similar apparatus, contained in a box, 
so that it is portable. 

The current which is given by the apparatus described 
may be varied, by adjusting the position of the slider, 
between a fraction of a milhampere and 300 milliam- 
peres, so that it is suitable for all purposes for which a 
constant current has to be applied direct to the body — 



SHUNT RESISTANCE 



41 



viz. ionisation, electrolysis, etc. Its voltage can be 
varied between zero and a maximum of about 80. 




Fig. 21. — Galvano-faradic Outfit 



The current that is taken by the apparatus from the 
main is not large, and it may be taken with safety from a 
lamp-holder or wall plug. 



42 ESSENTIALS OF MEDICAL ELECTRICITY 

A more elaborate switch-board is shown in Fig. 21. 
A volt-meter and a milliampere-meter are fitted so that the 
voltage and amperage of the direct current that is sup- 
phed to the patient can be measured. There is also a 
reverser, so that the direction of the current may be 
altered as desired. An induction coil is also fitted. It 
is worked by the current from the main, suitably reduced 
by the lamp shown on the top left-hand corner of the 
board. Either the faradic or the direct current can be 
led to the two binding screws shown at the bottom of the 
board, and thence to the patient, according to the adjust- 
ment of the de Watteville key shown on the left side of 
the board just above the induction coil. 

The volt-meter is not essential, but it is very con- 
venient to have. It shows the difference of potential 
between the electrodes applied to the patient, and by its 
use rough approximations of the resistance between the 
electrodes can be arrived at by taking the reading in volts 
and milliamperes and working it out by Ohm's law. 

The direct current from the main may also be used for 
heating the cautery, but here again it requires modifica- 
tion. A cautery has a very low resistance, a small 
fraction of an ohm, which is very much lower than that 
of the body. Therefore a much lower voltage is required. 
Two volts will usually be sufficient, while that of the 
main current (100 to 250) is far too high. On the other 
hand, the cautery requires a high amperage (say 12 to 18), 
which is higher than that of the current supplied to 
houses for lighting purposes and very much higher than 
that of the current given by the apparatus described 
above (viz. a maximum of 300 milliamperes, or 0*3 
ampere). Neither this apparatus nor the unaltered 
main current are suitable* for cautery. It is possible, 
however, to obtain a cautery current from the main by 
using an apparatus of the same type as that described, 
but modified in the following way. The shunt resistance 



SHUNT RESISTANCE FOR CAUTERY 43 

should be much lower, and should consist of fewer turns 
and of stouter wire. A lamp is not included in the 
circuit, as it would add too much resistance. A slider 
is fitted so as to move along the shunt resistance 
and so regulate the amount of current that is taken 
to the cautery. For finer regulation a rheostat (a vari- 
able resistance) is inserted between the slider and one of 
the terminals leading the current to the cautery. A 
plan of the device is shown in Fig. 21. It has the 
disadvantage of being very wasteful of current. For 




Adjustable 
RheoiUt 



Fig. 22. — Shunt Resistance for Cautery 

this reason a small lamp is inserted, as shown in the 
figure, to act as a signal that the current is flowing so that 
it may be turned off when it is no longer required. This 
lamp, it will be seen, is inserted in shunt with the resist- 
ance not in series with it, so that it will only take a very 
small proportion of the current. 

Another disadvantage is that it cannot be connected 
to a lamp-holder or wall plug. It takes a very large 
current (because the shunt resistance is low and no amp 
is included in series with it), and if it were connected to 
a lamp-holder or wall plug the safety fuse would melt 
and the current would be cut off. If the practitioner has 



44 ESSENTIALS OF MEDICAL ELECTRICITY 

not heavy cables taken into his house from the street 
mains specially adapted for heavy currents, he will have 
to derive the cautery current from accumulators or from 
a machine known as a " motor generator " or " motor 
transformer." This is a combination of an electric motor 
and a dynamo or generator. The current from the main 
causes the revolution of the motor, which in its turn 
actuates the dynamo. The djmamo generates the new 
current and it can be wound so that this current has the 
voltage and amperage desired. The motor generator is 
illustrated and further described on p. 45. 

For the illumination of surgical lamps like those fitted 
to the ophthalmoscope, cystoscope, etc., we require a 
current of lower amperage than for cautery, but higher 
voltage. If the lamp filament is long and thin it will 
have a higher resistance, and the current must be at higher 
voltage. Short, thick filaments have a lower resistance 
and require a lower voltage, but a higher amperage if it 
is to be raised to incandescence. 

For quite small lamps the apparatus first described, 
for providing currents suitable for direct application to 
the body, may be used. For larger lamps, accumulators 
or a motor generator should be used. Or a suitable shunt 
resistance constructed on the same plan as that for 
cautery may be used. It must be seen that the current 
which it takes is not heavier than that for which the house 
cables are intended to carry. 

The direct current from the main is also suitable" for 
working the large induction coils used for the production 
of high-frequency currents and X-rays. These coils 
usually take more current than that carried by the 
cables passing to a lamp-holder, so that it is generally 
necessary to fit heavier cables. 

For the diathermy machine the direct current is un- 
suitable. It must be converted into an alternating 
current. This is done by a motor transformer, and one 



UNIVERSAL APPARATUS 45 

must be used that can provide an alternating current of 
at least 10 amperes at 100 volts. The current that is 
taken by this transformer is heavy and cannot be carried 
on the house cables. Specially heavy cables must be 
taken into the house from the street main, sufficient to 
carry 20 amperes. 

The use of a shunt resistance for lowering the pressure 
of the main current is not unattended by risk. The risk 
lies in the possibility of accidental short-circuiting to 
earth and so obtaining a much larger proportion of the 
main current than is desired, or even the whole of it, 
with disagreeable or disastrous results. How this risk 
is possible will be explained on page 52, together with 
the precautions necessary for avoiding it. By using a 
motor generator this risk may be avoided. Manu- 
facturers of electro-medical apparatus now make forms 
of so-called " universal " apparatus. Such apparatus 
contains a motor generator, and by its use it is possible 
to derive from the main constant and sinusoidal currents, 
and currents suitable for cautery and electric lamps. 
Different forms of " universal " apparatus are sold 
under the names of " Pantostat," " Polystat," " Multo- 
stat," according to the maker. A Pantostat is shown in 
Fig. 10. Mounted on the left side of the base is the 
motor generator. It is connected to a wall plug or lamp- 
holder. The constant current from the main causes the 
revolution of the motor, and two new currents, quite 
distinct and separate from the main current, are formed. 
(The principle of the motor generator is described on 
page 292.) Of these two new currents one is a constant 
current, suitable for direct application to the body, 
either through electrodes or by means of the bath. Since 
this current is on a circuit quite separate from the main 
circuit, risks of shocks are avoided, as short circuit- 
ing is impossible. The other current is an alternating 
current. This can be varied in strength and appUed to 



46 ESSENTIALS OF MEDICAL ELECTRICITY 

the body in the same way as the constant current. Or 
it can be taken to static transformers (contained in the 
base of the machine) and transformed into currents 
suitable for cautery and lamps. As with the constant 
current, there is the same freedom from the possibility 
of shocks through short-circuiting. 

On the base of the machine are two switches and a 
milliampere-meter. One of the switches reverses the 
direction of the constant current. The other is for the 
purpose of leading either the constant current or the 
sinusoidal, or both together, to the patient or for cutting 
oil all current. The continuous and sinusoidal currents 
are taken to the right-hand pair of terminals. The left- 
hand pair lead off the cautery current. The two middle 
pairs lead off the current for illuminating lamps, one pair 
for small lamps, the other for larger lamps. Five shding 
rods can be pulled out from the base of the machine : one 
regulates the strength of the current passing to the 
motor ; the others regulate the strength of the currents 
for cautery and light, and the sinusoidal and constant 
currents. 

The Use of the Alternating Current from the Main. — 

The voltage at which this current is supplied on the mains 
differs in various towns and districts. In some it is lOO ; 
in others it is as high as 250. The amperage of the 
current taken into the houses for lighting purposes is the 
same as for the direct current. The periodicity is not the 
same for every town. In some it is 25 ; in others it may 
be as high as 100. 

The alternating current is very suitable for cautery 
heating and for lighting lamps, and for stimulation of the 
body. It is necessary for diathermy. It cannot be used 
for ionisation or electrolysis or for operating induction 
coils. 

As with the direct current, the first requirement is the 



STATIC TRANSFORMER 



47 



reduction of the voltage and amperage when it is to be 
appHed to the body. This may be done by a shunt 
resistance as described for the direct current, but a much 
more satisfactory way is to use a " static transformer." 
By means of this the current from the main and that 
passing to the patient are quite separate from each other, 
so that risks of shocks from short-circuiting are not 
possible. Regulation of the strength of the current pass- 
ing to the patient can then be easily effected by inserting 



AUfi-TTW-ttvig 

Correut 

Main 




pjACMt 



Fig. 23. — Scheme for derivation of current from alternating 
current main by way of a transformer, and regulation of current by 
means of a resistance either in shunt (R^) or in series (R^). 

a shunt resistance or series resistance in circuit with 
the patient. A scheme of the arrangement is shown in 
Fig. 23. 

A static transformer consists of a core of soft iron, around 
which are wound two separate coils of insulated wire. 
One of these coils is called the primary coil, the other the 
secondary. These coils form quite distinct and separate 
circuits. The alternating current from the main passes 
through the primary coil, and as it oscillates to and fro 
induces another alternating current in the secondary. 
It is not possible, with proper insulation, for the main 
current in the primary coil to get into the secondary 



48 ESSENTIALS OF MEDICAL ELECTRICITY 



coil. The voltage and amperage of that induced in the 
secondary depends upon the number of turns of wire 
in this coil, as compared with the number of turns in the 
primary. If there are fewer turns in the secondary, 
the induced current will be of lower voltage and higher 
amperage (suitable for cautery and lamps) ; if there are 
more turns in the secondary than in the primary, the 
induced current will be of higher voltage and lower 

amperage. This 
transformer is 
called a 5^/zc trans- 
former, as it has 
no moving parts, 
unlike the motor 
transformer. 

A static trans- 
former suitable for 
deriving a current 
for cautery and 
light is shown in 
Fig. 24. The 
transformer is 
fixed to the upper 

rr. r r X . , , ^ P^rt of thc board. 

Fig. 24. — Transformer for JLight and Cautery ^^ ,. 

^ ^ The alternatmg 

current , taken from a lamp-holder or wall plug (the primary 
coil of the transformer takes a current of about 2 amperes), 
passes to the primary coil of the transformer. On the 
secondary coil is wound a smaller number of turns of 
wire so that a current of lower voltage and higher am- 
perage (also alternating) is induced in it. This current 
which is suitable for heating cautery and has an am- 
perage of about 18, is led to the two terminals on the 
bottom left-hand corner of the board. 

There is another secondary coil also wound over the 
primary, and the number of turns is arranged so that a 




SINUSOIDAL CURRENTS FOR TREATMENT 49 

current of about 2 amperes at 15 volts is induced in it. 
This current is suitable for lighting lamps. It is led to 
the terminals at the bottom right-hand corner of the 
board. The cautery current and the light current may 
be regulated according to the requirements of the instru- 
ment or lamp used. The regulation of each current is 
effected by a "rheostat " (a variable resistance). Each 
rheostat is made of a coil of resistance wire, and a variable 
length of it can be included in the circuit (in series) by 
altering the position of the slider. The upper rheostat 
is for the cautery current, the lower for light current. 
For both of these currents the voltage has been lowered. 
The transformer is therefore known as a " step-down " 
transformer. 

A sinusoidal current suitable for use in electric baths 
can be also obtained from a static transformer. The 
secondary of the transformer is wound so that the voltage 
of the induced current is high enough to overcome the 
resistance of the baths in the circuit. Usually it has to 
be raised ; the transformer is then a " step-up " trans- 
former. Regulation of this induced current can be 
effected by means of a shunt resistance of the same kind 
as that used for lowering the voltage and amperage of 
the direct current from the main (described in the early 
part of this chapter) or by a series resistance. Another 
way of regulating the current is to lead it through a coil 
of wire, like the primary of an induction coil, and let it 
induce another current in a separate coil that can slide 
over the primary as a sledge (like the secondary of an 
induction coil). This last current is taken to the patient 
and its strength can readily be regulated by sliding the 
secondary over the primary. 

By means of a motor the secondary can be made to 
slide backwards and forwards over the primary, and so 
produce rhythmic variation of the current supplied to the 
patient. A device of this kind, made by Gaiffe, of Paris, 



r 



50 ESSENTIALS OF MEDICAL ELECTRICITY 

has been in use in the electrical department at St 
Bartholomew's Hospital for some years, for supplying a 
sinusoidal current to three arm baths placed in series. 
It requires very little attention and there is no risk 
whatever in using it. 

For the purpose of electrolysis, ionisation, etc., for 
which an alternating current cannot be used, some 
method must be adopted for converting the alternating 
into a constant (direct) current. This can be done by 
means of a motor generator adapted so as to work when 
supplied by an alternating current. " Universal " 
apparatus is made so as to take an alternating current, 
and it will then provide the currents that have been 
mentioned under the description of the Pantostat. 

The direct current supplied by the Pantostat is not 
sufficiently strong for the operation of large induction 
coils for X-ray work or high frequency. For these 
purposes it is necessary to use a more powerml motor 
generator. 

For operating the diathermy machine an alternating 
current is required, and the voltage of this current should 
be 100 and the amperage not less than 10. The cables 
that are fitted to a house for ordinary lighting purposes 
would not take a current of this strength. It is therefore 
necessary to introduce cables into the house that can 
take 20 amperes. 

The alternating current cannot be used to charge 
accumulators on account of its repeated change of 
direction. There is a device known as the "Aluminium 
Rectifier " which will allow the passage of a current in 
one direction, but not in the other. If, therefore, it is 
included in the circuit of an alternating current, only 
those portions that pass in one direction will be allowed 
through, and the current will now flow only in one 
direction. It will, however, not be constant, but 
intermittent. 



ALTERNATING CURRENT RECTIFIERS' 51 

The rectified alternating current can be used for many 
purposes for which continuous currents are necessary. 
For charging accumulators some authorities consider it 
superior to constant current, and as a result of consider- 
able experience the author is inclined to agree with this 
view. It will drive continuous current motors quite 
satisfactorily and can be adapted to operate large spark 
coils so as to give excellent results. It is not smooth 
enough for direct apphcation to patients. 

Rectifiers are of two kinds — chemical and mechanical. 

Chemical rectifiers depend for their action on the 
pecuHar property of aluminium in that it offers a very 
high resistance to the passage of a current when it is 
made the anode of an electrolytic cell, at the same time 
it offers no particular resistance when it becomes the 
kathode. 

A rectifier maybe made of a jar containing a saturated 
solution of ammonium phosphate in which are partially 
immersed, without touching, a rod of aluminium and 
another of iron. A current is able to pass through 
the solution from iron to aluminium, but not from the 
aluminium to the iron. 

By means of a small cell of this kind an accumulator 
can be charged direct from the alternating main and left 
going all night, and in that way the battery kept charged 
and always ready for use. It is impossible for this 
rectifier to get out of order under ordinary circumstances, 
and it is quite independent of any temporary interruption 
of the main current. They are made of various sizes, 
the larger of which can be used for large sparks coils 
and for direct current motors, as well as for charging 
accumulators. What is known as the Nodon Valve is a 
rectifier constructed on this principle. These rectifiers 
have to be made very bulky when currents of any 
magnitude are passed through them, otherwise they 
become very hot. 



52 ESSENTIALS OF MEDICAL ELECTRICITY 

Mechanical Rectifiers, — These are really motor trans- 
formers of which the motor part is constructed so that 
it can be worked by an alternating current. A direct 
current is then generated. The makers of "universal 
apparatus " construct types that can be operated by the 
alternating current. The direct current which they give 
is suitable for direct application to the body, in baths, 
or by means of ordinary electrodes. It is not sufficiently 
strong for the operation of large spark coils, such as are 
used for the production of X-rays. For this purpose 
larger motor transformers of the same kind must be used. 

Dangers attending the Use of Currents derived from 
the Mains. — ^At this stage it will be well to point out 
the risks that are run when current derived from the 
main is used for medical treatment, and show how they 
arise and how they may be avoided. 

In all cases where patients are being treated by means 
of electricity derived from the street mains, there are 
certain precautions which must be observed to prevent 
accident. On account of the voltage and amperage of 
the main current, it is always possible to give unpleasant, 
even dangerous, shocks. Even if such an accident should 
not be attended with serious results, it is very disconcert- 
ing to all concerned, and patients sometimes strongly 
resent even slight shocks if they have not been warned 
beforehand. Carelessness in this respect leads to loss of 
confidence on the part of the patient, and possibly even 
the loss of the patient. 

To understand why it is possible to obtain shocks when 
the current from the main is used, even with a shunt re- 
sistance, attention must be paid to the way in which the 
current generated in the power station is distributed 
along the mains. A system of distribution known as the 
three-wire system comes from the generating station in 
the form of a three-wire cable. One of these is the 



HOW SHORT-CIRCUITING IS POSSIBLE 53 

positive, another is the negative, and the third is neutral 
and acts as a common return to the others. All three 
are insulated from each other. The neutral is positive 
to the negative wire, and negative to the positive wire, 
and, by a rule of the Board of Trade, must be connected 



/O 




— cable (eorirLcO) ~ 

Fig. 25 

to earth. Consumers are supplied from the neutral and 
one or other of the other two. The earth is a good 
conductor of electricity. Anything that is connected 
to earth by a conductor (" earthed " is the customary 
expression), such as metal water-pipes, radiators, electric- 
light fittings, streams of water coming from pipes (metal 
or rubber), stone floors, wooden floors when damp, is 



54 ESSENTIALS OF MEDICAL ELECTRICITY 

therefore connected to one of the main cables (the neutral 
one). Now if the patient is in connection with the other 
cable he has only to touch any one of the objects named, 
or touch the operator, who is himself touching one, to get 
the current from the main through him. The same 
thing will happen if the patient has damp boots resting 
on a wet floor or on water-pipes or other earthed objects. 

It is therefore necessary that a patient under treatment 
should be so disposed that no conductor connected to 
earth is within his reach. The floor should be quite dry, 
and, if it is made of wood or stone, should be covered 
with some non-conducting material, such as linoleum. 
It must not be forgotten that water containing substances 
in solution (and therefore a conductor) may drip out 
from the damp pads and moisten the floor, and make its 
way between adjacent pieces of the non-conducting 
material covering the floor, thereby establishing an 
earthed contact for the foot to touch. 

In the diagram (Fig. 25) is shown a patient receiving 
treatment by a direct current taken from the main, with 
a shunt resistance interposed, as described in the early 
part of this chapter. Two of the main cables are seen 
under the ground, and one of these (the neutral) is 
connected to earth. Suppose that the first cable is 
positive, the neutral cable becomes negative to it. 
The + cable is insulated from everything. A shunt 
resistance, BA, and lamp are shown and are supposed 
to be in a room. When the main current is switched 
on it passes from the insulated -l- cable up into the 
room, through the lamp, then through the shimt re- 
sistance, BA, then back to the earthed negative cable. 
CDFE is the circuit that includes the patient (Pt.). 
Part of the current passes through this circuit. Let us 
suppose that the patient is earthed (touching a radiator 
or water-pipe or electric switch, or standing on a non- 
insulating stone floor, or a damped wooden floor ; or he 



HOW SHORT-CIRCUITING IS POSSIBLE 55 

may be touched by a friend who is earthed) . The current , 
instead of taking the path described, can travel through 
the lamp, along the shunt resistance as far as D,then to 
the patient at F, then through the patient to earth and 
the negative cable. But no shock will be felt, because 



r^ 




— coble (eaTTkfid) ^ 
Fig. 26 

the resistance of the patient is probably not less than that 
of the portion of the shunt resistance, DC, which the 
current has avoided. But when D is placed closer to B, 
a shock will probably be felt. Now suppose that the 
current from the main is taken to the shunt resistance 
in the opposite direction. This may readily be done by 
altering the position of the two-point plug that leads 



56 ESSENTIALS OF MEDICAL ELECTRICITY 

the current to the shunt resistance. Reference to the 
diagram shown in Fig. 26 shows that a short circuit will 
be formed through the patient if he is earthed and he will 
then receive the full pressure of the current from the 
mains. The current will pass from the positive cable to 
A, along CE to the patient, pass right through his body 
to earth, missing out the entire length of the shunt 
resistance, AB, and the resistance of the lamp. 

Such an accident could be prevented by making the 
plugs so that they can be fixed in only the correct position. 
It is safer to have two resistance lamps instead of one, and 
place the other on the other side of the shunt resistance, 
so that the current has to traverse it before entering the 
former at A. An additional precaution, which should 
always be taken, is to make the current pass through two 
lamps that are permanently in position on a switch- 
board on the waU before entering the other lamps and 
shunt resistance. It is always advisable to use two 
lamps, because if the filament fuses the metal may fall 
across and make a short circuit at the base of the lamp, 
and so cut out most of its resistance. If there is only 
one lamp, the sudden increase in the strength of the 
current passing through the shunt resistance and the 
patient would cause a shock. There is another possibility 
of accident, as the resistance wire may break, and if the 
breakage occurs between A and D (Fig. 25) the current 
must aU traverse the patient to get back to the negative 
cable. The shock that the patient receives is not likely 
to be severe, unless there is a greater length of wire 
included between A and D. This risk may be almost 
completely avoided by using two shunt resistances con- 
nected in parallel, so that the current traverses both 
simultaneously. 

If the precautions mentioned above are taken, the 
direct current from the main may be used for application 
to the body, either by means of pad electrodes or the 



AVOIDANCE OF DANGERS IN BATHS 57 

Schnee bath. Accidental shocks, though disagreeable, 
are never fatal, because the current is applied only to 
relatively small portions of the body. In the case of the 
full-length bath the case is different. Here the patient 
is quite devoid of any protection which a dry skin or 
clothing might otherwise afford him, and is also quite 
unable to help himself quickly when immersed in the 
water of the bath. If it is desired to apply the direct 
current from the main to a full-length bath, the pre- 
cautions already mentioned have to be taken, and, in 
addition, the bath itself must be completely insulated 
from earth. 

To thoroughly insulate the bath is practically impos- 
sible in the case of those already fixed, but it is quite 
feasible if the bath is installed with that end in view. 
The one at the London Hospital was done this way and 
is satisfactory. The bath itself is of porcelain. Large 
rubber pads about one inch thick are placed between the 
bath and the cement pedestals upon which it rests. Part 
of the waste-pipe consists of a length of rubber hose — 
leakage of current may occur here along the thin layer of 
water left in the pipe, but its resistance is high enough 
to prevent any such leakage worth troubling about. 
The water-pipes are kept clear of the bath and discharge 
from a point high up out of the reach of the patient. 

The late Dr Lewis Jones considered that "no method 
which depends for its safety upon the maintenance of 
insulation from earth of a bath containing water is good 
enough to risk." If it is desired to use the direct current 
from the main in the full-length bath, the safest way is 
to use the motor transformer like that suppHed on the 
" Pantostat," etc. Motor transformers that are used 
for this purpose must have the wire of the armature of 
the motor quite separate and perfectly insulated from 
that in which the direct current is generated. 

At St Bartholomew's the direct current is not supplied 



58 ESSENTIALS OF MEDICAL ELECTRICITY 

to any of the fuU-length baths, the alternating (sinu- 
soidal) current being used instead. As explained before, 
the inclusion of a static transformer removes all risks 
of short circuits to earth. After the current has been 
switched on and regulated, the patient requires no 
further attention. There has been no accident or failure 
since the baths were first installed. Another advantage 
of this freedom from risk is that continued attention to 
the patient while in the bath is not necessary — an 
advantage which is specially to be considered in busy 
hospital practice. 

Supply from Private Installation. — ^Where current 
from the main is not available some other source of 
supply must be sought. 

If it is intended to use electricity more or less exten- 
sively, of course the best way is to install a dynamo and 
drive it by means of a gas, oil or steam engine, or even 
a water turbine, if such power is available. The current 
could be used direct, but it would be found more con- 
venient to charge accumulators with it and use the 
current from them. In this way the engine need only be 
run for a few hours on two or three days a week, and the 
current will be available at all times. Where space is a con- 
sideration, a very compact little plant can be obtained, 
composed of a petrol engine, such as used on motor 
bicycles, coupled direct to a dynamo suitably designed 
for the purpose. A set to give 15 amperes at 60 volts 
meets most medical requirements in a private practice 
or small hospital, and runs very satisfactorily. In all 
cases the dynamo should be provided with sUp rings, 
so that alternating current can be obtained when 
necessary. 

While the upkeep of a small private plant as above 
indicated is not very costly, the initial outlay may prove 
an insurmountable obstacle. If there is a place in the 



SUPPLY FROM ACCUMULATORS 59 

neighbourhood where cells can be charged, then 
accumulators should be used. 

Supply from Accumulators. — ^The construction and 
mode of action of accumulators is described on page 270. 
Accumulators provide a current of low voltage and high 
amperage, and are therefore particularly suitable for 
heating cauteries and lighting lamps. They can be 
readily obtained, packed in portable cases. Two to four 
connected in series will be sufficient for cautery and light ; 
and six will provide a current strong enough to work a 
spark coil as well. The strength of the current that is 
required can be adjusted by a rheostat attached to the 
case. The current from accumulators can be used for 
applications to the body, but as a higher voltage is 
necessary to overcome the resistance of the body, a 
number must be connected in series. The weight of 
such a battery would be very heavy ; it is therefore 
more usual to use a battery of dry cells when a direct 
application of the current to the body is to be made. 
Such a battery is described in the next paragraph. 

A dozen 4- volt batteries such as used for motor bicycles, 
could be arranged to meet most medical requirements by 
means of a multiple switch, which would put them all in 
parallel, for cautery or light, and all in series for direct 
application to the body — with a shunt resistance. 

Another method of utilising the high pressure direct 
current mains is to charge an accumulator therefrom 
through a resistance and then use the accumulator 
independently. This system has many advantages for 
certain purposes. It enables one to keep a battery 
charged which can be taken about and used for cautery, 
light, or working an X-ray coil. With the direct current 
laid on, the charging of a battery is most simple. A 
special plug is provided which is fitted with a lamp- 
holder so that lamps of different resistance may be used. 



6o ESSENTIALS OF MEDICAL ELECTRICITY 

From this plug runs a double flexible conductor. Having 
ascertained which one of these is positive it should be 
marked so as to avoid confusion in the future. This end 
must always be connected to the + terminal of the 
battery and the other one to the - terminal. A i6 c.p. 
lamp should be placed in the lamp-holder and the plug 
inserted. The accumulator may be connected up to 
the main when the day's work is done and left going aU 
night when suflicient energy will have been stored up 
to last one or more days according to the demand made 
upon it. 

As the resistance lamp used glows with almost its full 
candle power there is no reason why it should not be 
arranged to take the place of one of the lights regularly 
used in the house. In this way the charging of the 
accumulator costs practically nothing. 

Supply from Primary Batteries. — If none of the 
sources previously mentioned are available, the supply 
may be obtained from primary batteries. Dry ceUs are 
now almost always used. Batteries of these cells packed 
away in wooden cases are now extensively used, and by 
reason of their portability, cleanliness and freedom from 
risk of shocks by short-circuiting to earth, are convenient 
for those for whom a main supply of current is not 
available. The cells wiU last for two years with average 
use before they require to be replaced by fresh ones. . 

Primary batteries of dry cells will provide a current 
suitable for application to the body, as for electrolysis, 
ionic mediation, etc., and for the lighting of smalllamps. 
The amperage of the current is not sufficient for heating 
cauteries or driving spark coils for X-ray work or high 
frequency. For these purposes batteries of bichromate 
cells (page 272) are suitable. Such batteries can now be 
obtained in portable cases. They are heavier than the 
dry-cell batteries and require more frequent recharging. 



DRY CELL BATTERIES 



6i 



although the owner can recharge them himself if he has 
a stock of potassium bichromate and sulphuric acid. 

Portable Dry Cell Batteries. — ^These batteries can be 
obtained from any instrument -maker. The number of 
cells that they should contain will depend on the purpose 




Fig. 27 

for which the current is required. For application of 
the current to the mucous membranes, 8 to 12 will be 
enough. For application to the skin, a larger number 
will be required. A battery of 32 will be suitable for 
almost all cases for which the direct application -of the 
galvanic current to the body is desired. Fig. 27 shows 
such a battery. The case also contains a milUampere- 
meter, a current reverser, and a current collector. By 



62 ESSENTIALS OF MEDICAL ELECTRICITY 

means of the latter, the strength of the current can be 
increased or diminished by including a larger or smaller 
number of cells in the circuit. 

It consists of a metal arm pivoted in the centre of a 
disc upon which are arranged as many studs as there are 
cells in the battery. These studs are insulated from each 
other and arranged in a circle, so that the metal arm as 
it is rotated comes successively into contact with the 




Fig. 28 

studs.^ The ceUs are all joined up in series, but a wire 
has to be brought from each junction to one of the studs, 
to which they are joined in regular order. In this 
arrangement the first cells are always used, those at the 
other end are used only when the strongest current is 
required. Hence the first cells are exhausted soonest, 
and then they form a useless resistance for the other 
cells to traverse. 
The double collector. Fig. 28, is an improvement on 



DRY CELLS AND SHUNT RESISTANCE 63 

this, enabling any group of cells to be used at will. It 
has two cranks mounted on the same axis but insulated 
from each other. One crank is connected to the 
positive and the other to the negative terminal. An 
index is fitted to one of the cranks which shows at a 
glance the number of cells in action at any moment. 
Next to the shunt resistance it is the best method of 
controlling the current from a battery of this kind. 

The current collector does not allow absolutely even 
regulation of the current. The current increases step 
by step as cell after cell is taken into the circuit ; these 
sudden increases cause pain when sensitive parts, such 
as the alveoli of the teeth, are subjected to them, but 
are not felt when the current is passed through the skin 
in less sensitive parts. 

A shunt resistance allows the most perfect regulation 
of the strength of the current. The cells are joined 
together in series and the current from the total number 
is passed through a rheostat. The current for the body 
is shunted off from the rheostat and its strength is 
regulated by moving a slider along the latter, the method 
being the same as that adopted for the regulation of the 
drect current from the main. 



CHAPTER IV 

THE BODY AS A CONDUCTOR OF ELECTRICITY 

Resistance of the Body. — ^When an electric current 
traverses the body, it encounters its chief resistance in its 
passage through the skin, the soft tissues and organs 
underneath opposing its flow to a much lesser degree. 
The resistance of the skin var'es within wide limits, while 
that of the underlying parts is relatively constant. The 
explanation of these facts will be apparent when it is 
remembered that the conductivity of the tissues is due 
to the presence of ions. The skin is poor in ions, their 
number varyiag considerably, according to the condition 
of the skin ; the underlying tissues and organs contain 
abundance of ions, and their proportion is relatively 
constant. 

The outermost layer of the skin is the horny layer, and 
if it is quite dry, and if the electrodes in contact with it 
are dry metal, there will be no ions to conduct the current 
through the skin. If this current is the constant current 
and at a voltage not higher than that at which it is usually 
applied for medical purposes (say '50-70 volts), it will be 
unable to overcome the resistance of the skin and no 
current wiU flow. If, however, the sweat glands secrete, 
the dry skin will be moistened and contain ions, and 
some current will flow. If the skin is moistened with 
salt solution, as is customary before applying the elec- 
trodes, its resistance is artificially reduced, by reason 
of the diffusion into the horny layer of water containing 
ions. 

The resistance and the body will vary also according 

64 



RESISTANCE OF THE BODY 65 

to the size of the electrodes ; if the latter covers a large 
area of skin there will be a large area of entry for the 
current and the resistance will be lower. The distance 
between the electrodes will also influence the resistance ; 
the longer the path for the current, the greater the resist- 
•ance, and vice versa. 

It wiU be seen, then, that the resistance of the body 
depends upon a number of factors and can vary within 
wide limits. If the constant current is used and is sent 
from one hand to the other, along the upper extremities 
and across the trunk, the hands being immersed in salt 
solution, the resistance may be taken as about 1300 ohms. 
When the resistance of the skin is excluded, the residual 
resistance is much less. Some experiments by Weiss 
showed that the resistance from shoulder to shoulder was 
40 ohms, and from elbow to elbow was 250 ohms, when 
the skin resistance was excluded. 

If the current is allowed to flow for some time and the 
metals of the electrodes be separated from the skin by 
pads soaked in salt solution, ions will actually migrate 
into the skin, and the resistance of the latter will pro- 
gressively diminish, till it reaches its lowest value at the 
stage when it is permeated with ions. The phenomenon 
wiU be frequently observed during the process of medical 
ionisation ; the needle of the mHUampere-meter will be 
seen to move gradually across the scale, showing that the 
strength of the current is increasing owing to the diminu- 
tion of the skin resistance. If, however, the moistened 
pads contain ions that will form insoluble compounds 
when they come in contact with ions in the skin, the 
reverse will take place ; the needle will move in the 
opposite direction, showing a fall in the current strength. 
The resistance of the skin has increased because the 
number of ions in it has diminished. 

The thick skin of the pahns and soles has a higher 
resistance than the thinner skin elsewhere. Patients 



66 ESSENTIALS OF MEDICAL ELECTRICITY 

who have been long confined to bed have a high skin 
resistance, because the horny layer is less readily shed 
and therefore thicker. 

The body offers less resistance to currents that are alter- 
nating or intermittent, flowing for very brief periods in any 
one direction before interruption or reversal. Thus the re- ' 
sistance of the body is much less for f aradic currents, and 

currents that alternate 
with a high frequency. 
The writer has measured 
the resistance of some 
hundreds of patients to 
the f aradic current, pre- 
vious to taking electro- 
cardiographic records, 
and has found it to vary, 
in different individuals, 
from 500 to 700 ohms. 
The resistance was taken 
from elbow to elbow, the 
forearms being immersed 

Fig. 29.— Diagram to indicate diver- ^ ^^^^ solution. The 
gent lines of flow of constant current faradic and alternating 
through tissues, with greatest density of currents do not alter the 
current immediately under electrodes, ^^^^entb GO noi aiier ine 

resistance of the skin like 
the constant current, because they do not cause a 
migration of ions into it. 

Path of the Current in the Body.— When the current has 
passed through the skin it encounters much less resistance 
in the underlying tissues. The path of least resistance 
will be the shortest path between the electrodes, and 
more of the current will pass that way, but some will 
take more circuitous paths, because, having a choice of 
several paths, it will distribute itself between them, the 
amount going by each one being inversely proportional 




PATH OF CURRENT IN BODY 



67 



to its resistance. Some of these paths will loop out to 
each side (Fig. 29) beyond the parts enclosed between 
the electrodes, and the amount of current flowing along 
these paths will be less as the loops become wider and 
the paths between the electrodes become longer. It 
will be evident then that the deeper a tissue lies the 
smaller will be the share that it will receive of the whole 
current passing between the electrodes. The density of 
the current (that is, the amount of the current traversing 
a unit of sectional area at right 
angles to its path) will be greatest 
at the points of its entry and 
exit, and least at a point half- 
way between. 

If we imagine the current of 
electricity to be made up of 
thin lines or strands, where the 
density is greatest they are 
gathered together as in a cord. 
If the cord is frayed out the 
density is less, but the same 
number of lines are there. In 
its passage from one electrode 
to the other no lines are lost, 
but some of them will take a very circuitous route 
before being finally gathered in at the other electrode. 
If one electrode is larger than the other the density 
will be greater at the smaller. A certain minimum 
density of current is necessary to produce appreciable 
physiological or therapeutical results, and one may safely 
say that with the currents used in medical electricity the 
density in the outlying regions away from the direct 
line between the electrodes is so slight as to be of no 
importance. 

If the electrodes are placed both on the same side of 
the trunk or a limb, the lines of flow of the current wiU 




Fig. 30 



68 ESSENTIALS OF MEDICAL ELECTRICITY 



dip down into the deeper parts (Fig. 30), but the density 
of the current will be greatest under the electrodes and 
in the superficial parts, but very slight in the deeper parts. 
Very little current will travel in the skin itself between 
the electrodes on account of its high resistance. If the 
electrodes are placed on the same side, but farther apart, 
more of the current will flow through the deeper parts 
than if they are placed closer 
together (Fig. 31). 

It is important to remember 
the divergent path taken by the 
current between the electrodes. 
It explains why it is that a 
stronger current is required to 
stimulate a deep-lying muscle 
or nerve. Tissues that lie be- 
neath the surface receive only 
a portion of the whole current, 
and a portion that becomes 
progressively smaller the deeper 
they lie. The divergent path 
taken by the current is one of 
the reasons why ions cannot 
be taken, from without, into the deep-lying organs in 
sufficient number to be of therapeutic value. 

The milliampere-meter gives information of the total 
amount of current passing through the body, but not 
the amount passing through any one part of it. 

The divergent path that has been described is that 
taken by the constant current. It is probable that 
currents which oscillate with a high frequency do not 
take such a path, but confine their course to the part 
l5dng between the electrodes, without spreading to those 
lying on each side. 




Fig. 31 



Anode and Kathode. — ^The anode is the electrode by 



ANODE AND KATHODE 



69 



which the current passes into the body (it may be 
remembered as the " in-ode ") ; the kathode is the 
electrode by which the current passes out of the body. 
In physiological experiments, in which we use excised 
muscle and nerve and place the electrodes in actual 
contact with them, the current is confined to them and 
there is one anode and one kathode, each locaUsed to the 
point of contact of electrode with tissue. In the case 
of the body the conditions are quite different, and it is 
impossible to place the electrode or electrodes in actual 
contact with the muscle or nerve which is to be stimulated. 



Anode 




Sorf<i.cft oj- 
/ skin. 



\ It /^ K 1^ {LXi^^r skin. 



Fig. 32 

but only at a distance from them with the skin and fasciae 
intervening. Further, the muscle and nerve are not 
isolated, but in contact with tissues on all sides. These 
tissues all conduct the current, and it is therefore impos- 
sible to localise the current to the muscle or nerve or to 
localise anode or kathode to the region immediately 
under the electrode. There will be, instead, a number 
of anodes and kathodes scattered over the surface of the 
muscle or nerve. Fig. 32 shows, diagramatically, an 
anode overlying, but not in contact with, a muscle 
that is below the skin. It will be seen that on the side 
of the muscle facing the electrode there are a number 
of anodes, and a number of kathodes on the side away 
from the electrode. The current density will be greater 
on the side facing the electrode, so that when the latter 



70 ESSENTIALS OF MEDICAL ELECTRICITY 

is, say, the anode, we are stimulating the muscle not 
with an entering current only, but with a leaving current 
as well, the former, however, being at a greater density 
than the latter. 

Conduction of Currents at High Voltage. — ^The voltage 
at which the constant current can be applied to the body 
for medical purposes is not high and the current is 
dependent on the tissue ions for its conveyance through 
the body. If, however, the voltage is very high, as is the 
case with static electricity, the tissues are able to conduct 
the current like solid conductors, from atom to atom as 
well as through the agency of the ions. 



CHAPTER V 

IONIC MEDICATION 

Definition. — It has been shown in Chapter I. that the 
results that follow the application of the constant 
(galvanic) current are to be attributed to the behaviour 
of the ions as they conduct the electricity. Ionic medica- 
tion would, therefore, in its widest sense, include many 
of the branches of medical electricity, but the teixn is 
generally used for that form of treatment in which an 
electrical current is used for the purpose of introducing 
the ions of soluble medicinal substances into the body. 
The term " cataphoresis " is occasionally used instead 
of " ionic medication," but it should be reserved for 
another physical phenomenon that occurs during the 
passage of the current through the tissues — viz. the 
gradual passage of water from the region of the anode 
to the region of the kathode. Cataphoresis plays no 
essential part, so far as is known, in the process of ionic 
medication. 

The meaning of the term " ion," and the way in which 
the ions can be made to move by the electrical current 
has been considered in Chapter I., and the process 
there described is that which is now generally believed 
to be that which takes place. Under the heading of 
Ionic Medication are grouped (i) the introduction of new 
ions from without, (2) the production of caustic bodies 
from the ions present within the body, (3) the alteration 
in the distribution of the ions already present within 
the body. The first of these will be now described. 

The Use of the Electrical Current for Introduction of 

71 



72 ESSENTIALS OF MEDICAL ELECTRICITY 

Ions into Body. — ^There is enough experimental evidence 
to prove that ions can be carried into the body by the 
electrical current. The lithium ion and the iodine ion 
have been made to pass through the skin and have been 
detected in the urine and saliva. The strychnine ion 
can be made to pass through the skin of an animal and 
cause convulsions, and the cyanide ion (CN) can be 
similarly introduced and cause rapid death. The entry 
of these poisonous substances is not by diffusion, because 
control animals with pads soaked in solutions of strychnine 
hydrochloride or potassium cyanide in contact with the 
skin are not affected if the current does not flow, nor 
are they affected if the current flows and the pads are 
connected to the wrong pole of the source of current. 
Cocaine ions may be made to pass into the skin and 
cause local anaesthesia. Here again the anaesthesia is 
not developed so long as the current does not flow. 

Another good illustration of the power of the current 
to cause the ions to penetrate is seen when an ulcer is 
treated by zinc ions. The application of a dilute solu- 
tion of zinc sulphate to the granulations at the base and 
edges produces no result that is visible to the eye. But 
if the solution is connected to the positive pole of a source 
of constant current, and the latter allowed to pass for 
ten minutes, the granulation tissue acquires a pearly 
white colour not only on the surface but in the deeper 
parts. This white colour is due to the formation of a 
compound of albumen and zinc. The zinc ions have 
entered, and many have entered into combination with 
the proteins. 

Advantages of the Ionic Method. — The method of 
introduction of drugs, or, more correctly speaking, their 
ions, by the electrical current has special advantages 
which are possessed by no other method. The current 
passes into every part of the tissue that is to be treated, 



ADVANTAGES OF THE IONIC METHOD 73 

and the ions travel along the same paths. Suppose, for 
example, an infected ulcer is to receive treatment by an 
antiseptic, such as zinc sulphate. If a solution of this 
salt is placed in contact with the ulcer, it will exert its 
germicidal action only on the surface, because it can 
penetrate only by diffusion, which process is very slow. 
If, however, the solution is connected to the positive pole 
of a battery, the zinc ions are now carried into the tissue. 
Every part with which the solution makes contact will be 
penetrated by the electrical current, so that all the cells 
and their intercellular spaces will receive the zinc ions. 
There is the further advantage that by using the 
electrical current, only the therapeutically active ion is 
taken in. In the case of zinc sulphate and the infected 
ulcers, the zinc ion, only, is taken in, and the SO4 ion 
passes in the opposite direction. The refusal of some 
chronic ulcers to heal when germicidal solutions are 
placed in contact with them in compresses, and their 
prompt response and progressive healing after the intro- 
duction of the ions by the electric current, is frequently 
noticed by those who have experience of the ionic method 
of treatment. 

Another advantage of the method is that the ions are 
introduced only into the region where they are wanted. 
If a drug is taken by mouth it is absorbed into the blood 
and is distributed to aU parts of the body, and here 
again when it passes through the capillary walls it has to 
diffuse into the cells. By the ionic method it is taken in 
by the current. 

Limitations of the Method. — ^The use of the electric 
current for the introduction of ions has this limitation — 
only the more superficial tissues receive them in numbers 
sufficient for therapeutic action. The deeper the part 
that requires treatment, the smaller the number of 
ions it receives. The reasons for this are the following. 



74 ESSENTIALS OF MEDICAL ELECTRICITY 

In the first place, the current, in its passage through the 
skin and into the tissues, does not confine itself to the 
shortest path between the points of its entry and exit, 
but takes divergent paths into the deeper parts. The 
ions take similar divergent paths and so spread farther 
apart as they penetrate the deeper tissues. In the 
second place, the deeper the penetration the greater the 
number of blood vessels and l3niiphatics that may be 
encountered, and if any ions pass into the circulating 
fluid they will be carried away. Lastly, if the ions of the 
heavy metal are being introduced, they may come in 
contact with others in the tissues, with which they may 
unite and form insoluble compounds, and so are thrown 
out of solution. 

When ions are introduced for the treatment of, say, a 
large joint, it cannot be expected that many, if any, will 
reach the deepest parts, and such beneficial results as 
are obtained are due, in part, to some ionic change and 
redistribution taking place in these regions, as well as to 
the action of the ions introduced into the superfic parts 
of the joint. 

Depths of Penetration of Ions. — ^The depth to which 
an ion will penetrate depends, first, on the duration of 
the flow of the current ; the longer the period of flow 
the greater the depth of penetration. Secondly, on the 
electro-motive force at which the current is supphed — a 
greater electro-motive force will drive the same ion 
farther, in the same time, than a lesser electro-motive 
force. Thirdly, on the ion ; those composed of elements 
of low atomic weight will penetrate further than those o^ 
wh'ch the component elements have a high atomic 
weight, the time o' current flow and the electro-motive 
force being the same for each ion. 

Physical experiments have been carried out to 
determine the actual depth of penetration of ions into 



DEPTH OF PENETRATION OF IONS 75 

non-living material. An electrical current was made to 
traverse a jelly containing sodium and chlorine ions to 
make it a conductor, and take in with it hydrogen ions 
from a solution of hydrochloric acid. The depths to 
which the hydrogen ions migrated was indicated by the 
decolorisation of the phenol-phthalein with which the 
jelly was tinted. The hydrogen ion was found to have 
travelled io-8 mm. in one hour, with an expenditure of 
I volt of E.M.F. along each centimetre. Sodium travelled 
1-26 mm. in the same time, potassium 2-05 mm. and 
chlorine 2* 16 mm. With an expenditure of 10 volts along 
each centimetre the distances are ten times as great. 

In the case of the tissues the conditions are different, 
and, such as they are, diminish the depth of penetration. 
The lines of flow of the current diverge and the ions 
therefore pass laterally as well as directly forward ; 
other ions enter the blood and lymph streams and are 
carried away ; others combine with tissue ions and may 
form insoluble compounds and therefore pass no further. 
The depth, therefore, to which ions penetrate into the 
tissues is not the same as for inert, simple substances, 
like the jelly in the experiment described above, and is 
probably less, and cannot be calculated from the factors 
given above. An experiment by Gautier showed that a 
current of 20 milliamperes was able, in ten minutes, to 
take copper ions into and through the wall of the uterus 
of a rabbit. Finzi introduced ferrocyanide ions through 
the skin over the knee joint of a monkey, and using a 
current of 10 milHamperes for thirty minutes was able 
to detect the ions in the cartilage of the joint. 

Apparatus required for Ionic Medication. — ^For the 
practice of ionic medication we require : (i) A source of 
electric current. (2) Cords to conduct the current to the 
body. (3) Electrodes to lead the current from the cords 
into the body and, at the same time, hold the solutions 



76 ESSENTIALS OF MEDICAL ELECTRICITY 

of the drugs the ions of which are to be introduced. 
(4) Solutions of the drugs, 

(i) The Source of Current. — The current must, of 
course, be a consta?it current. It should be possible to 
regulate its strength between zero and a maximum, 
which, when the body is in circuit, and the conditions are 
those under which ionic medication is carried out, should 
reach a value of 100 milliamperes at least. To send such 
a current through the body an E.M.F. of at least 50 
volts is necessary, though for a smaller current a lower 
voltage will do. 

The constant current is sometimes called the con- 
tinuous or galvanic current, and when obtained from the 
main is known as the direct current, or, for short, DC. 

If the current from the main is available, and if it is a 
direct current, this will be the most useful and economical. 
Although this current, as supplied for domestic purposes, 
is much too strong for medical purposes, it can be suit- 
ably reduced, and the method of doing so is described 
on page 37. There is no risk of shocks to the patient 
or operator if the precautions detailed on page 54 are 
taken. 

If there is no main supply, much can be done with 
a portable battery of dry cells. These batteries are 
described on page 60. When there is private plant for 
generating electricity, the current required may be taken 
direct from the dynamo. Or the dynamo may be used 
to charge accumulators. The current may then be 
taken from the latter when required. In this way 
the dynamo need be worked only on occasions when 
convenient. 

If accumulators are used, a number of them must be 
connected in series, so that the voltage of the current 
may be sufficiently high to overcome the resistance of the 
body. 



APPARATUS FOR IONIC MEDICATION ^^ 

(2) The Cords that conduct the current to the body 
should be made of flexible stranded copper wire covered 
by insulating material. It is essential that the latter 
should be waterproof, because it is certain that they wiU 
be accidentally wetted sooner or later, and then the 
copper will gradually corrode and break. Further, the 
wire is no longer insulated where it is wetted, and if it 
should touch the patient's skin the current wiU pass out 
and form an additional circuit and perhaps cause blisters 
at the point of contact. A flexible stranded copper wire 
with its ends securely soldered into firm metal end- 
pieces of larger diameter may be enclosed within a 
narrow rubber tube ; the free ends of the latter are 
stretched over the end-piece, making a waterproof cover- 
ing of the soldered joint, but leaving the end free, so that 
it can be fixed to the binding screw of electrode or 
battery. Cords of this kind have been used during 
the past few years in the electric department at St 
Bartholomew's and have proved to be very satisfactory. 

(3) The Electrodes. — ^The electrodes consist of two 
parts: [a] an absorbent pad, which is soaked in the 
solution containing the ions ; (6) a metal plate of rather 
smaller area than the pad and bearing a binding screw 
for attachment of the cord. 

The pad that contains the solution should be made of 
absorbent material, such as lint, glass cloth, towel or 
Gam gee tissue. It should be of a thickness correspond- 
ing to sixteen layers of Unt. Separate strips or layers 
can be placed one over the other, or a large sheet may be 
folded and refolded till it has the desired thickness. 

The metal plate, to which is attached the cable, may 
be made of sheet brass. Aluminium may be used, but is 
more likely to break after much bending. The metal 
plate may be placed direct on the pad, but if a layer of 
felt is placed between, the layers of lint may be reduced 



78 ESSENTIALS OF MEDICAL ELECTRICITY 

to eight. The felt should be a quarter of an inch thick, 
and it should be of larger area than the metal, so as to 
overlap it half-an-inch all round. The felt should be 
stitched to the metal, and, for this purpose, the edges of 
the plate should be perforated for the passage of needle 
and thread. These perforations should be one-eighth of 
an inch wide and placed in pairs, at the corner, and, if 
necessary, at the sides. The felt has to be taken off 
frequently for cleaning, and it takes less time to stitch 
it on if the metal plates are perforated as described 
than if small holes are drilled all the way round the edge. 



■RutWr covtr 

cord 



Sttanacd u.,^^ Conducl.ng 




Fig. 33. — Diagram of Electrode 

These felt-covered metal plates are useful for other 
electro-medical purposes as well. 

An electrode is shown in section in Fig. 33. 

The absorbent pad should be of sufficient size to cover 
the part that is to be treated. The felt should be of 
smaller size than the pad, while the metal plate should 
be smaller than the felt. 

When the electrode is in position the pad is in contact 
with the skin, and the felt, with the metal, rests on the pad. 
It will be seen that with this arrangement the metal is 
situated some distance off the skin. The importance 
of this will be evident when it is recollected that, as 
described in Chapter I., new ions possessing caustic 
properties are formed at the points where the solid and 
the fluid conductors are in contact. At the metal plate 

+ 
of the electrode that forms the kathode, Na and OH ions 
are formed. The latter are repelled from the kathode 



THE SOLUTIONS 79 

towards the skin. If the pad and felt are thin, they will 
finally reach the skin, and, being caustic, will, if in suffi- 
cient concentration, cause burns. In the case of the 
anode, ions of the metal forming the plate lying on 
the absorbent pad, wiU migrate towards the skin. If the 
pad is thin they will soon reach it. In some cases it is 
intended that the ions of a metal shall be introduced, 
but not necessarily those of the metal forming the 
electrode (copper and zinc when the electrode is made 
of brass). In other cases, positively charged ions other 
than those of metals (quinine ions, for example) are to 
be introduced, and in these cases the ions of the metal 
forming the electrode are not desired. A pad like that 
described is sufficiently thick to hold sufficient solution 
and an ample supply of the ions to be introduced. 
At the same time the ions of the metal part of the 
electrode will not have time to reach the skin as the pad 
is sufficiently thick. 

(4) The Solutions need not be more than 1% in 
strength. It must not be thought that more ions will be 
introduced if the solution is stronger. The stronger the 
solution the larger the proportion of undissociated 
molecules. Stock solutions of 10% strength may be 
made and diluted with ten times the bulk of water when 
required for use. Tap- water may be used if it is not 
" hard." If it is hard, and contains much carbonate or 
bicarbonate, precipitates will be formed if it is used to 
dilute zinc salts. To allow for this, the zinc salt may be 
diluted rather less, or distilled water may be used. The 
ions present in the tap-water will be introduced at the 
same time, but there is no evidence that they produce 
any appreciable effect. 

In some cases the substance to be introduced need not 
be already in the ionic state before the current is passed. 
For example, if the zinc ion is to be introduced, we may 



8o ESSENTIALS OF MEDICAL ELECTRICITY 

use the metal itself instead of a solution of one of its salts, 
and connect it to the positive pole. When the current 
passes, the metal slowly passes into solution, so that its 
ions are formed. Those ions then migi-ate into the 
tissues. It is more convenient to use the metal when 
parts difficult to reach with the solution — e.g. sinuses — 
have to be treated by the ionic method. 

The Ions used in Medicine. — ^These may be arranged in 
two tables, according to the charge which they bear. 
Against each ion is placed the salt from which it may 
be most conveniently obtained, and the strength of the 
stock solution. 

Ions with - Charge {known sometimes as " Anions ") 

Chlorine (Cl). From solution of common salt. 

(The salt is best stocked in the solid condition, 

and a solution of three teaspoonfuls to a pint 

of water made when required.) 
Iodine (I). From solution of potassium iodide 

or lithium iodide (io%). 
Salicylic ions. From solution of sodium salicylate 

(10%). 

Ions with + Charge {known sometimes as " Rations ") 

+ 
Zinc (Zn). From a solution of zinc sulphate 

(10%). 

+ 
Magnesium (Mg). From a solution of magnesium 

sulphate (io%). 
+ 
Lithium (Li). From a solution of lithium chloride 

(io%), or lithium carbonate. (The latter is 
only slightly soluble.) 
+ 
Silver (Ag). From a solution of silver nitrate 

(io%). (Distilled water should be used.) 



PRACTICAL APPLICATION 8i 

+ 
Copper (Cu). From a solution of copper sulphate 

(10%). 

+ 
Mercury (Hg). From a solution of mercuric 

chloride (io%). 

Quinine. From a solution of quinine hydro- 
chloride (io%). 

Cocaine. From a solution of cocaine hydro- 
chloride (io%). 

Adrenalin. From a solution of adrenalin chloride 
(i in looo). 

Practical Application. — If the part to be treated lies 
under the skin, the latter should be first freed from greasy 
secretion by washing with soap and water and then 
thoroughly rinsed. Or the skin may be wiped with 
ether or acetone. Any skin lesion should be covered by 
a scrap of waterproof material, such as thin sheet rubber 
or adhesive plaster. The pad, soaked in the solution, 
diluted to a i% strength and sufficiently wrung out, 
so that it does not drip, is placed on the grease-free 
skin, so as to make good and even contact all over. It 
is very important that there should be good contact all 
over. The metal with the attached felt is soaked in the 
same solution and placed on the pad, bent, if necessary, 
so as to make good apposition. The two are then 
securely fixed, by means of a bandage. The connecting 
cord from the battery is then attached to the metal 
plate binding screw. This is known as the " active " 
electrode. 

In order to complete the circuit, another electrode is 
required. It is exactly the same as the active electrode, 
and it is soaked in salt solution. It is placed on some 
convenient part of the body, away from the active 
electrode. In area it should be equal to or larger than 



Sz ESSENTIALS OF MEDICAL ELECTRICITY 

the active electrode, never smaller. It is known as the 
" indifferent " electrode. 

If more than one part is to be treated, we may use two 
" active " electrodes, and place one over each part. A 
different ion will, of course, be taken in from each elec- 
trode, one electrode being positive, the other negative. 
The two active electrodes should be of the same area. 
Or, two or more active electrodes may be used, and one 
indifferent electrode. In this case two or more conduct- 
ing cords wiU be required, one to each active electrode. 
The area of the indifferent electrode should be equal to or 
larger than the united area of the active electrodes. 

The pole of the battery or other source of current 
to which the active electrode or electrodes should be 
attached depends upon the electrical charge of the ion 
that is to be' driven in. Pads containing ions with the 
positive charge (kations) are connected with the positive 
pole of the source of current. Ions with the negative 
charge (anions) are placed in the pads connected to the 
negative pole. 

When the circuit is completed the current is started. 
It must always be started from zero, slowly and gradu- 
ally increased till the maximum is reached, at which it 
may stay for the period of the treatment. It is then 
gradually diminished till it reaches zero. The sudden 
switching on of the current or the sudden switching off 
will cause the patient to feel a smart shock, and must 
be avoided. The too rapid increase in strength of the 
current, or the too rapid diminution, will cause pain 
without shock. 

When the current has reached a small value the patient 
feels a pricking, tingling sensation. It soon disappears, 
and as the current is further increased he begins to per- 
ceive a hot, burning sensation over the whole pad. This 
again diminishes, but when the current is increased 
beyond a certain value the sensation persists, and the 



lONISATION THROUGH SURFACES 83 

current should not be further increased. The maximum 
value should not be more than 2-3 mHUamperes per 
cubic centimetre {i.e. 12-18 per square inch). If the 
patient persistently complains of burning pain locaUsed 
to one spot, it may mean that excessive current is being 
concentrated there (owing to uneven contact of pad and 
skin, or uneven soaking of the pad), and the current 
should be slowly decreased to zero and the pad and skin 
examined. 

It wiU be noticed that when some ions are being driven 
in, the current, as indicated by the miUiampere -meter 
needle, will show a spontaneous increase in its strength. 
This is because the saturation of the skin with ions 
reduces the resistance of the latter to the lowest value. 
On the other hand, other ions, like those of the heavy 
metals, form insoluble compounds with the tissue ions, 
so that the current-conducting ions are diminished in 
number and therefore the milHampere -meter needle 
moves back towards zero. 

If the ions have to be introduced into a tissue from 
which the epithehum or superficial fascia has been lost, 
such as a wound or ulcer, any scabs or crusts should be 
first removed and the surface then swabbed with water 
or saline to wash away discharge. The pad should then 
be evenly appHed to the cleaned surface. If the surface 
is very irregular, the uniform contact without leaving 
any part untouched may be secured by withdrawing, 
with a dissecting forceps, small portions of cotton wool 
from a roU, dipping them in the solution and placing them 
in the crevices and irregularities till they are fiUed and a 
smooth surface obtained, to which the lint pad may then 
be appUed. 

lonisation of Sinuses. — ^The ionisation of sinuses is 
more difficult, because it is less easy to ensure contact 
between the electrode and every part of the wall. If the 



84 ESSENTIALS OF MEDICAL ELECTRICITY 

ions of zinc, copper or other metals are to be introduced, 
a rod of the metal covered by lint soaked in a solution of a 
salt of the metal may be inserted into the sinus down to 
its end. If the sinus is narrow, the uncovered metal may 
be used. An alternative method is to pass a fine brass 
tube, filled with some antiseptic solution, such as zinc 
sulphate (i%), down the sinus to its end, attach a 
syringe filled with the same solution to the end of the tube 
and force the solution from the end of the tube, at the 
same time slowly withdrawing the latter, but not com- 
pletely. The tube is then passed again to the end of the 
sinus and the process repeated. By this method there is 
more hkelihood of the solution coming into better con- 
tact with the wall of the sinus, and less chance of any 
part escaping contact with it. A terminal is attached 
to the tube, so that the latter can be connected to the 
battery or source of current. 

When connected to the positive pole, zinc ions migrate 
into the walls of the sinus. At the same time the metal 
of the tube gradually dissolves, forming ions, so that 
further ions (zinc and copper, from the brass) migrate 
into the wall. 

If it is wished to try the disinfectant action of ions 
other than those of metals, the metal tube must be con- 
nected to the proper pole of the battery. Thus if the 
salicyUc ion is used the tube is connected to the negative 
pole. 

The lonisation of Less Accessible Regions. — ^Different 
methods have to be adopted if ions have to be introduced 
into less accessible parts. If the walls of a cavity, such 
as the maxillary antrum, are to be ionised, the cavity is 
first filled with the solution containing the ions (after a 
preliminary wash out with water) , by means of a metal 
tube OP catheter. The metal tube also seirves to conduct 
the current into the solution within the cavity. It must 



lONISATION OF RECTAL WALL 85 

be carefully insulated, except at the point wheie it is 
inserted into the cavity. Otherwise the current wiU pass 
into any other part with which the tube may happen to 
be in contact. The insulation may be brought about by 
sliding a rubber tube over the metal. 

For ionising the wall of the rectum for ulceration 
and inflammation different methods are used. One 
method is to insert a zinc rod, six inches long, and 
covered by four layers of lint soaked in zinc sulphate 
solution (Wallace & Ironside Bruce). In another 
method a special electrode devised by Herschell may be 
employed. It consists of a copper or zinc wire bent to 
the form of a close spiral, enclosed in a rubber tube closed 
at one end, with a side opening near this end. The 
rubber tube with the enclosed spiral is contained in a 
larger membrane bag, which is wrapped closely round it. 
The whole is introduced into the rectum, with only the 
end projecting. Zinc sulphate solution can be made to 
flow, by gravity, slowly into the rubber tube from a 
douche can sufficiently elevated. It passes through the 
perforation and unwraps and distends the membrane bag 
into contact with the walls of the rectum. The metal 
spiral is connected to the positive pole of the source of 
current. Zinc ions migrate through the membrane into 
the rectal wall. A similar apparatus may be used for the 
vagina. 

The mucous membrane of the colon may be ionised, in 
cases of colitis. Curtis Webb has described a method. 
An electrode made of a wire spiral, twelve inches long, 
enclosed in a rubber tube closed at the distal end and 
provided with a side opening near this end, is inserted as 
high up the colon as possible through the anus. Two in- 
different electrodes are used ; one is placed on the front of 
the abdomen, the other on the lumbar region. They are 
connected to the negative pole of the source of current. 
From a douche can a hot solution of zinc sulphate 



86 ESSENTIALS OF MEDICAL ELECTRICITY 

(2%) is gradually run through the rubber tube con- 
taining the spiral. It slowly fills the rectiun and colon. 
The current is switched on and gradually increased till it 
reaches 15-20 milliamperes. It is allowed to flow for ten 
to fifteen minutes and then gradually turned off. While 
the current flows, more of the solution should be allowed 
to flow in, so long as the patient tolerates it. The wire 
spiral is connected to the positive pole of the source of 
current. 

In all cases where the interior of the bowel or other 
cavity is to be ionised, it is advisable to wash it out 
beforehand with warm water (distiUed, if silver nitrate 
is to be used afterwards), so as to remove substances 
which might combine (like pus, for example) with the 
solution afterwards introduced ; the lavage further clears 
away any substance in contact with the wall of the cavity. 

Duration of Ionic Treatment. — The duration of each 
session of treatment will vary according to the case, and 
definite times cannot be given. If a very sHght thickness 
of tissue is to be ionised, as in the case of a corneal ulcer, 
the session need not last longer than a minute and a half 
or two minutes. If the part to be ionised lies some 
distance below the surface, such as the sciatic nerve, the 
session should last longer, even as long as an hour. 

The interval between two successive sessions of treat- 
ment — ^when more than one is necessary — also depends 
upon the case. When ions like zinc, copper, etc. , that have 
caustic properties are used for treatment of sores and raw 
surfaces, the treatment should not be repeated until a 
week or ten days have elapsed. When ions that have 
no caustic action are used and the part to be treated lies 
under the skin, the sessions may be more frequently 
held, even every other day. If the erythema and slight 
degree of tenderness that follows each session have 
subsided, the treatment may be repeated. 



IONIC MEDICATION Sy 

The foregoing is a brief account of the princip es of 
ionic medication, and the way in which it may be carried 
out. In Chapter XIV., in which the most suitable 
electrical treatment for different diseases and morbid 
conditions is set forth, reference will be found to those or 
which ionisation is the method recommended. 



CHAPTER VI 

SURGICAL lONISATION — ^THE USE OF THE ELECTRICAL 
CURRENT FOR DESTRUCTION OF TISSUE 

Principle of the Method. — It has already been shown 
that new ions make their appearance at the points where 
the current leaves the anode to enter the electrol5rte, and 
where it leaves the electrolyte to reach the kathode. 
Hydrogen ions are formed at the anode (if the latter is 
made of platinum) and hydroxy! ions (OH) at the 
kathode. In addition, there is some free undissociated 
hydrochloric acid at the anode and caustic soda at the 
kathode. These ions and molecules have a caustic action 
and, as they migrate away from the electrode at which 
they are formed, precautions have to be taken, as described 
in Chapter V., to prevent them reaching the skin. When, 
however, it is wished to make use of their caustic pro- 
perties for the destruction of tissue, special arrangements 
can be made for the purpose. The details differ accord- 
ing to the tissue that is to be treated, but the principle 
of the method is as follows. The electrodes consist of 
metal only. They are made of very small size and take 
the form of needles, so that, in the first place, the current 
will be very concentrated where it enters and leaves the 
tissue, and the number of ions formed at these points will 
be sufficiently large to produce caustic effects. In the 
second place, the needles are inserted into the tissue, so 
that the caustic action can be localised in the situation 
desired. If the needles are made of platinum the ions 
liberated will be hydrogen at the anode, and hydroxyl 
at the kathode. If the needle forming the anode is made 

S8 



REMOVAL OF SUPERFLUOUS HAIRS 89 

of zinc or copper, then zinc ions or copper ions (not 
hydrogen ions) will be formed at the anode ; being 
present in concentration around the needle, they will 
exert a caustic action. 

In carr5dng out surgical ionisation we may use one 
active electrode and an indifferent electrode ; the latter 
is of the same kind as that described in the last chapter 
(page 77). The active electrode may consist of a group 
of needles, instead of a single needle, and all are connected 
to the same pole of the source of current. The indifferent 
electrode can be replaced by a needle or group of needles 
which are connected to the opposite pole, so that all the 
electrodes are active. 

The destruction of tissue by the ions liberated by the 
electric current is sometimes spoken of as electrolysis, 
and the action of the current as electrolytic The 
electrolytic action is really a chemical action of the ions 
liberated by the current. With regard to the method, 
its great advantage lies in the fact that only so much of 
the caustic as is wanted is produced, and the caustic is 
made in the area where its effects are desired. The 
action is thus exactly localised and under perfect control. 

It has been employed for the removal of superfluous 
hairs, warts, moles, destruction of naevi, strictures and 
cancerous growths, in the treatment of fibro-myoma of 
uterus, and to produce coagulation in an aneurysmal sac. 

The cases for which surgical ionisation is a suitable 
method of treatment will now be mentioned together 
with the method that may be adopted for each. 

Removal of Superfluous Hairs. — ^For this purpose the 
caustic ions and molecules forming round the kathode 
are used to destroy the hair follicle. To do this success- 
fully a good light is necessary. The indifferent electrode 
— the anode — is placed on any convenient part of the 
patient's body. The other pole is connected to a needle- 



go ESSENTIALS OF MEDICAL ELECTRICITY 

holder to which is attached a fine platinum needle. 
The needle should be not thicker than o-2 millimetres 

(Fig- 34). 

The current is best derived from dry cells. With a 
battery box like that described on page 6i, the current 
collector can be turned so as to take four cells into the 
circuit. The circuit should be completed, so that the 
current flows when ths needle reaches the folHcle. 

The operator steadying the hair with the forceps 
introduces the needle into the follicle passing in the 
proper direction alongside the hair. The needle enters 
from one-sixth to one-eighth of an inch. In about five 
seconds or so a slight effervescence is seen at the orifice 
of the folhcle, and the needle is withdrawn. The hair 



Fig. 34. — Epilation Needle fixed to Holder 

should come out by very gentle traction. If not, the 
needle may be inserted again for a couple of seconds. The 
point of the needle must not be too sharp. A dull point 
finds its way down into the follicle more easily. Platinum 
needles should always be employed and sterilised in the 
flame of a spirit lamp before use. There is a sharp 
stinging pain at the moment the needle is in the follicle, 
but it is not so severe that an anaesthetic is necessary. 
The local application of cocaine is useless unless intro- 
duced by the ionic method ; even then it is not advisable. 
When a large number are to be removed, only from 
twenty to thirty should be done at a single sitting, and 
these should be removed from over the whole surface. 
If this number were removed f rom-one spot a troublesome 
ulcer might result and leave a scar. The successful use 
of this method requires both practice and skill. Under 
the best conditions a certain number of the hairs return 
and have to be removed again. 



TREATMENT OF N.EVI 91 

If the temiinal quarter inch of the needle is bent nearly 
to a right angle with the long axis of the holder, the view 
of the mouth of the follicle is less obscured by the holder 
and the needle is more easily inserted. The latter must 
be sufficiently stiff : for this it should be made of iridium 
rather stouter than 0-2 mm., with the terminal quarter 
inch 0-2 mm. in diameter. 

Naevi. — ^lonisation is a most valuable method of 
treating ijaevi, and in many cases the only satisfactory 
one. With practice the operation is under perfect 
control and the results in suitable cases are all that can 
be desired. The object is to break up the blood vessels 
and coagulate the blood therein without causing general 
necrosis and sloughing. 
The destruction of the 
vessels and coagulation 
of the blood is caused by 
the caustic ions formed 
around the electrodes. 

If the growth is sub- 
cutaneous, the skin is not to be interfered with in any 
way except for the minute openings where the needles 
are inserted. If the skin is also involved, a certain 
amount of scarring is unavoidable. 

There are two chief methods of carrying out the 
destruction of naevi by the ionic method — the unipolar 
and the bipolar methods. 

The Monopolar Method. — ^A large indifferent electrode 
is placed on any convenient part of the body and con- 
nected to the positive pole. The needle or needles are 
attached to the negative pole of the source of current and 
introduced into the naevus. 

Eig. 35 shows a holder with nine needles, one or more 
of which may be inserted as required. 

In a large nsevus they should be introduced evenly 




Fig. 35. — Needles for Electrolysis 



92 ESSENTIALS OF MEDICAL ELECTRICITY 

through the mass, and the indifferent electrode must be 
very large and accurately applied. Where individual 
vessels can be recognised, the needle should be made to 
pass near, or even transfix them. When the naevus is 
situated on the face or head, the current, in its passage 
through head and neck to reach the indifferent electrode, 
may cause shock and faintness and irregular breath- 
ing, especially in children. In the bipolar method the 
current is confined to the naevus and 
does not traverse the central nervous 
system. 

In all CcLses the current is to be turned 
on and off very gradually. The currents 
used are large and if the needles are 
suddenly removed without first lowering 
the current to zero a severe shock would 
result. The current should not exceed 
20 miUiamperes per inch of needle 
inserted. 

The Bipolar Method. — ^This is to be 
preferred in most cases and is best 
carried out by means of a bipolar needle- 
holder devised by Dr Lewis Jones and 
shown in Fig. 36. 
The two wires from a battery are joined to the two 
terminals shown. The internal connections are such 
that the needles are joined to the positive and negative 
poles alternately. Two, three, four, or five needles may 
be used, according to the size of the mass to be treated. 
From four to six cells are turned on and then the needles 
are pushed through the mass. A milliampere-meter must 
be in circuit and the current not allowed to exceed 
20 miUiamperes for each inch of positive needle inserted. 
Here again the needles should be of platinum and 
sterilised by heating to redness before use. The needles 
should be inserted parallel with the surface. They 




Fig. 36 



TREATMENT OF N^VI 93 

should then be partially withdrawn and pushed in again 
in a different direction. The process should be repeated 
several times, so that the needles explore all parts of the 
nstvus and break up its blood vessels. While this is 
being done watch is kept on the skin where the needles 
have pierced it, so as to avoid the risk of destroying it. 
Soon after the needles are inserted the tissues round them 
begin to change colour. Round the positive needles 
there is hardening and pallor and the needle tends to 
become fixed and difficult to withdraw. Round the 
negative needles there is frothing with hydrogen gas 
given off, while the needle itself gets very loose. The 
tissues tend to become dark and livid round the negative 
needles and on the first sign of this should be withdrawn 
and reinserted in a fresh place if the nsevus has not 
already acquired the firm consistency indicating complete 
coagulation. In using this holder, Dr Lewis Jones 
considered the current should not exceed 20 miUi- 
amperes per inch of positive needle, if sloughing is to be 
avoided. 

The application of the needle should continue till the 
naevus acquires a firm consistency. 

Other variations of the above-described methods and 
appliances are advised and used, but these given will be 
found quite satisfactory in nearly all cases. The pain 
is severe, and an anaesthetic is required in practically 
every case. For after-treatment a piece of antiseptic 
gauze is applied over the punctures with flexible collodion. 
If sloughing supervenes an antiseptic poultice is applied 
at first until the slough is cast off and the ulcer treated 
on general principles. Small naevi, not over one quarter 
of an inch in diameter, can be destroyed at a single sitting. 
When larger than this, two or more sittings may be 
necessary. 

The aim should be to destroy the naevus, either com- 
pletely or as far as possible, at the first sitting. As the 



94 ESSENTIALS OF MEDICAL ELECTRICITY 

tendency of most ngevi is to increase in size they should 
be treated at the earhest possible time, and special 
attention should be given to the margin in all cases if 
recurrence is to be avoided. 

It has been suggested that copper needles should be 
used in place of platinum, with the idea of depositing 
a salt of copper in the naevus. Good results are obtained, 
but the use of copper does not appear to have a special 
advantage over the metal usually employed. 

In treating port wine marks, a single needle is used 
connected to the negative pole. The indifferent electrode 
is positive and placed on the sternum or other convenient 
part. The needle is inserted into the skin vertically 
and a current of 3 to 4 miUiamperes passed for a 
short time. The area must be treated in a mrniber of 
sittings — the needle at each sitting being introduced at 
various points scattered over the surface, as is done in 
removing superfluous hairs. The obliteration of exten- 
sive port wine marks take a very long time, as the area 
treated at each sitting is small. 

Stellate Veins. — ^These are treated by passing a zinc 
needle, attached to a suitable holder for a short distance, 
say about one-eighth of an inch, into the central vein from 
which the others radiate. The needle is connected to the 
positive pole and the circuit is completed by placing the 
indifferent electrode on some other part of the body. 
A current of i milliampere is passed for one minute. 
The central vein is coagulated by the zinc ions and the 
radiating vessels disappear. A minute scab forms, but 
drops off in a few days, and leaves a minute scar, which 
afterwards becomes almost invisible. 

Warts. — ^These are treated in the way described for 
stellate veins. The zinc needle is made to transfix the 
base of the wart at the level of the skin. A current of 



TREATMENT OF MOLES, STRICTURE 95 

I milliampere for one minute is sufficient. If the wart is 
larger than about one-eighth inch in diameter it may be 
transfixed again, once or more, in different directions, and 
the same strength of current applied and for the same 
time. 

This treatment is very successful. The wart gradually 
shrivels and drops off in a week or ten days. 

The method described is sometimes called " zinc 
needling." 

Moles. — Hairy moles are best treated by removing the 
hairs in the way previously described. Much of the 
pigment will disappear when the hairs are removed. 
Moles that are not hairy can be removed in the way 
described for warts. 

Strictures of Urethra. — ^Very Uttle has been heard of the 
electrolytic treatment of strictures during recent years. 
It offers no very decided advantages, and if sufficiently 
strong currents are used to produce active destruction 
of the scar tissue at the stricture, it is attended with some 
danger. A large indifferent electrode is placed on any 
convenient part of the patient's body, and is connected 
to the positive pole. The active electrode consists of a 
catheter-shaped bougie, terminating in a bulbous enlarge- 
ment. The latter is left bare, and the stem is covered 
with insulating material — the whole being more or less 
flexible. One is shown in Fig. 37. 

At the outer end is provided a terminal for attaching 
it to the negative pole. The size of the largest bougie 
that will pass the stricture as well as the distance of the 
latter from the meatus, having been ascertained, a bougie 
electrode is selected two sizes larger, and a mark made 
on its shank corresponding to the distance of the stricture 
from the meatus. It is now passed down to the stricture 
against which it is held, but no force is to be used under Fig. 37 



96 ESSENTIALS OF MEDICAL ELECTRICITY 

any circumstances. The circuit is closed and the current 
gradually turned on until 5 or 6 miUiamperes are 
passing. The pressure on the bougie must be gentle, 
and in the direction of the urethra, otherwise a false 
passage may be made. The pressure is kept up until 
the bougie passes through the obstruction and into the 
bladder, when the current is to be at once gradually 
reduced to zero and the mstrument removed. 

This operation may have to be repeated at intervals 
of not less than three weeks. 

Another method is that of " linear electrolysis." The 
active electrode consists of a long, flexible bougie, in the 
middle of which is a projecting blade of platinum (not 
sharp). This blade is connected to a terminal at the 
oifter end. The leading end is fihform and serves as a 
guide. The instrument is introduced, and the blade 
pressed against the stricture. The current is gradually 
turned on until 10 miUiamperes is reached, which is 
sufficient in most cases. 

The method is one which might be termed " elec- 
trolytic incision." The instrument is pressed against 
the stricture until the latter is divided, which takes place 
in about thirty seconds. Strictures in other parts, such 
as the lachr3mial duct, eustachian tube, oesophagus, and 
rectum, have been treated by electrolysis with more or 
less success. The method differs in no essential particular 
from those given for stricture of the urethra. 

Uterine Fibromyomata. — ^A great deal has been written 
for and against this treatment of uterine " fibroids " since 
ApostoU pubUshed his method in 1882. 

The action is to destroy the uterine mucous membrane, 
which results in a reduction of the size of the uterus and 
a decrease of the haemorrhage. The most that can be 
gained in the great majority of cases is of a palUative 
character. 



ANEURYSM, MALIGNANT GROWTHS 97 

Apostoli used an internal positive electrode of platinum, 
and an indifferent electrode of moist china clay, and a 
current of from 50 to 80 milliamperes passed for 
from five to fifteen minutes. The method is not much 
employed now. 

Aneurysm. — ^The treatment of this condition by 
electrolysis has not been satisfactory. The best results 
in this country have been obtained by the late Dr John 
Duncan, of Edinburgh. It is only applicable in cases 
where ligature is impossible or attended by special 
risks. The great objection to the method is the necessity 
of piercing the wall of the sac with the risk of setting 
up haemorrhage. The needles must be insulated except 
at the points, so that no bare metal comes in contact with 
the sac during the passage of the current. Both positive 
and negative needles are introduced into the tumour, and 
large currents and long sittings are the rule. 

Malignant Growths. — ^In the hands of some workers 
good results have been obtained in the treatment of 
carcinoma and sarcoma. The method which appears 
to have been most successful consists in plunging into 
the cancerous mass one or more small rods of amalgamated 
zinc — a puncture being first made with a scalpel to 
permit of the insertion of the rod or rods. These are 
connected to the positive pole of the battery — a large 
indifferent electrode being arranged under the patient. 
A general anaesthetic is always necessary. Large 
currents and long sittings are the rule, and the whole 
proceeding is more or less elaborate application of the 
ions of zinc and mercury. Complete destruction of 
the growth takes place in the immediate vicinity of the 
anodes and atrophy in the area farther away. It is 
largely practised by Dr Betton Massey, of New York, 
who claims that he has had very good and encouraging 

G 



98 ESSENTIALS OF MEDICAL ELECTRICITY 

results in a large number of cases of inoperable malig- 
nant disease. The method has not been used to any 
great extent in this country, but it ought to be given a 
further trial. It does not prevent the occurrence of 
metastases. 



CHAPTER VII 

lONISATION IN DEEP-LYING TISSUES 

In the methods of treatment described in the two 
preceding chapters the constant current has been used 
for definite purposes : first, to take into the diseased part 
the ions of the drugs of which the therapeutic action is 
known ; secondly, to deposit the ions of caustic chemicals 
where desired, in order to destroy tissue. 

The constant current is known also to produce thera- 
peutic effects in general or local maladies in which its 
modus operandi is less evident. The effects are not due 
to the ions that are taken in from without, because these 
ions may have no therapeutic value. Thus the electrodes 
may be soaked in salt solution : under these circumstances 
sodium ions enter at the positive electrode and chlorine 
ions at the negative electrode. It is unlikely that the 
good results that follow the application of the constant 
current to a sprained joint, for example, are due to the 
entry of sodium ions from the positive electrode and 
chlorine ions from the negative electrode. Even if the 
ions of drugs known to be of value in the treatment of 
disease are contained in the electrodes, they are not 
likely to reach the deepest parts in the time during which 
the current is usually allowed to flow during a session of 
treatment. It is therefore necessary to seek some other 
explanation. The question must nevertheless be con- 
sidered from the point of view of the behaviour of the 
ions. The constant current causes a steady movement 
of the ions normally present within the tissues, either 
in the same direction as the current or in the opposite 

99 



100 ESSENTIALS OF MEDICAL ELECTRICITY 

direction, according to the charge carried by the ion. 
There must therefore be some redistribution of the 
tissue ions. It cannot be said whether such redistribu- 
tion has any therapeutic effect, but it is possible that 
there are ions of disease products in some morbid con- 
ditions, and if such is the case the constant current would 
cause their migration out of the tissue and into the 
vessels. A mode of action of this kind was suggested in 
Chapter I. to explain the disappearance of fatigue from 
tired muscles, following the application of the constant 
current. 

The migration of the ions acts as a stimulus, at any 
rate to some of the tissues, as, for example, the sensory 
nerves. The steady flow of the current through the skin 
causes a burning sensation as the ions pass through the 
sensory nerves. 

The erythema that is evident in the skin after the 
current has been passing through it shows that vaso- 
dilatation is produced. It is likely that there is some vaso- 
dilatation in the deeper parts also and possibly some 
stimulation of the tissues in the same region. In those 
maladies where the passage of the constant current 
produces cure or relief, the tissue stimulation and vaso- 
dilatation may be contributing factors. The passage of 
the current through a fluid effusion such as is found in a 
joint after injury is often followed by its disappearance. 
It is possible that this disappearance may be due to 
migration of ions from it and lowering of its osmotic 
pressure. 

To apply the current for treatment of diseases of the 
deep parts, electrodes like those described in Chapter V. 
for medical ionisation may be used — viz. absorbent pads 
for placing in contact with the skin and felt-covered 
metal plates for attachment to the cords leading from 
the source of current. They must, of course, be soaked 
in a solution of an electrolyte, so that ^they may conduct 



APPLICAtlOli^ M iCtJ^RSNj: ^ loi 

the current. Sodium chloride is used. If it is wished 
to introduce some special ion as well as to influence the 
deep parts, the pad is soaked in a solution containing the 
ion and connected to the correct pole. If sodium chloride 
is used, sodium ions will migrate inwards from the pad 
connected to the positive pole, chlorine ions from that 
connected to the negative pole. It is important that the 
electrodes should be of sufficient size so as to overlie 
the whole of the part requiring treatment. With smaU 
electrodes the maximum current density that the skin 
can tolerate is reached with a smaU current, and when 
this small current has spread along divergent paths in 
the deep parts the amount of current in any one part is 
very small. For application to the abdomen, an elec- 
trode that covers the whole of the anterior surface should 
be used, while another of the same size should be placed 
on the back. For application to the brain, one electrode 
(the kathode) is placed so as to cover the forehead, the 
other is placed on the back of the neck. For the spinal 
cord an electrode three inches wide and of a length 
equal to that of the part to be treated is placed over the 
vertebral column. This electrode is usually the kathode. 
The anode may be placed on the front of the chest, its 
total area of contact with the skin being not less than that 
of the kathode. 

If the shoulder is to be treated, it should be surrounded 
as far as possible by strips of lint soaked in the electrolyte, 
and a piece of felt-covered metal, bent so as to fit over 
the deltoid, placed in contact with the lint and bandaged 
in position. The other electrode may take the form of 
strips of lint wound round the forearm, with a felt-covered 
metal plate measuring, say, six inches long by two inches 
wide in contact with the lint, over the anterior or posterior 
surface of the forearm. If may be more convenient to 
dispense with the lint and immerse the forearm in a 
solution of the electrolyte in the arm vessel of a Schnee 



102 ESSENTIAXS OF MEDICAL ELECTRICITY 

bath (page 113). The solution takes the place of the 
soaked lint pad, while a metal plate immersed in it, but 
not in contact with the skin, connects it to the source 
of the current. If desired, the pad around the shoulder 
may contain the ions of a drug, which will then enter 
the superficial part of the joint where the latter does 
not lie deeply. The pad must be connected, of course, 
to the correct pole of the source of current. If it is not 
wished to introduce ions from outside, an alternative 
method of applying the current to the shoulder is to fix 
electrodes one to each arm, or to immerse each forearm 
in a Schnee bath. The current then passes through both 
shoulder joints. For the hip similar arrangements may 
be made as for the shoulder. If an electrode is placed 
over the hip, it should be of large area and pass round 
from the gluteal region to the groin, which should be 
overlapped. The other electrode should be placed on the 
leg, or the leg may be immersed in a Schnee bath. 

Another method of applying the current is to place one 
electrode over the front of the hip in the region of the 
groin and upper part of the front of the thigh, and the 
other electrode over the gluteal region. If both legs 
are immersed in the Schnee bath the current will traverse 
both hip joints and the intervening parts as well. 

Among the morbid conditions for which the application 
of the constant current produces good results may be 
mentioned congestion, particularly when the exciting 
cause {e.g. trauma) has ceased to act. The results are 
not at all likely to be due to the introduction of ions from 
without. Some cases of progressive muscular atrophy 
are benefited by application of the constant current to the 
spine. The same treatment often relieves the crises and 
pains of tabes dorsalis, and it is of value in some cases 
of neurasthenia and hysteria. Leduc recommends its 
application to the brain in cases of cerebral fatigue and 
exhaustion. 



lONISATION IN DEEP PARTS 103 

The diseases for which the appHcation of the constant 
current, " galvanisation " as it is often called, is suitable 
will be found in Chapter XIV. In these cases the current 
is not applied for the purpose of introducing new ions 
from without. 



CHAPTER VIII 

THE USE OF THE ELECTRICAL CURRENT FOR STIMULATION 
OF THE TISSUES ; ELECTRIC BATHS 

A VALUABLE property of the electric current when applied 
for the treatment of disease is its power to produce 
general stimulation of the tissues. Such stimulation is 
more effective if the current is rhythmically varied in 
strength and direction of flow. The experiments of 
Debedat on the stimulating action of different currents 
on the growth of muscle (see page 121) showed that a 
constant current produced only a slight increase in the 
size of the muscle, while a current that was interrupted, 
flowing for periods of one second, each period of flow 
being followed by a period of rest of equal length, caused 
an increase by 18%. In many diseases and morbid 
conditions the electric current produces good results by 
reason of its stimulating action on the tissues of the body. 
The continuous current causes a migration of ions wherever 
it flows ; the current if interrupted or reversed or modified 
in various ways causes, not a steady onward movement 
or migration of the ions, but interrupted movement or 
to-and-fro movement, or movement modified in accord- 
ance with the modification of the current. This irregular 
movement of the ions is a stimulus to the tissues of the 
body. Muscles will contract, nerves will be stimulated, 
and other tissues will be stimulated to give their custom- 
ary physiological response. The beneficial effects that 
follow the electrical treatment, by means of interrupted 
currents, of general maladies, such, for example, as 

104 



MODIFICATIONS OF CONSTANT CURRENT 105 

rickets or anaemia, or of the symptoms grouped under the 
heading of " general debihty " are to be attributed to the 
general stimulation produced by the current, or, as it 
should be said, by the ionic movement produced by the 
current. This power to produce general stimulation of 
the tissues is one of the most valuable properties of 
electricity in the treatment of general and local diseases. 

Modification of Current for Stimulation of Tissues. — In 

Chapter II. modifications of the constant current have 
been described, together with the ways in which they 
may be obtained from the constant current. These 
modifications may be tabulated and summarised as 
follows : — 

1. Simple Interrupted Current. — ^This is obtained from 
a constant current (from main, or battery of cells) by 
including in the circuit either — 

(a) A metronome interrupter. The current inter- 
ruptions are abrupt and infrequent ; 

{b) A Leduc interrupter. The current interruptions 
are abrupt . The frequency of interruption can 
be varied and the duration of the periods of 
flow and no-flow can be varied and measured. 

2. Simple Alternating Current. — ^This is obtained from 
a constant current (from main, or battery of cells) by 
including in the circuit a revolving Ruhmkorff com- 
mutator. The interruptions are abrupt, and short 
periods of rest occur between the reversals. The inter- 
ruptions and reversals are frequent and can be varied. 

3. Sinusoidal Alternating Current. — This may, in some 
districts, be supplied on the main. Otherwise it may be 
obtained from a constant current (from main, or battery 
of cells, or accumulators) by including in the circuit 
a motor transformer. The alternation is frequent ; there 



io6 ESSENTIALS OF MEDICAL ELECTRICITY 

is no period of rest between the reversals, and the rise of 
current strength from zero to maximum is not abrupt. 

4. Slow Sinusoidal Alternating Current. — This is 
obtained from a constant current (from main, or battery 
of cells, or accumulators) by including in the circuit a 
slowly revolving motor transformer or Ewing's rhythmic 
reverser. 

5. Faradic Current. — ^This is obtained from a constant 
current (from one or two dry cells, or, if desired, from the 
main, the current being suitably reduced) by including 
in the circuit an induction coil. The current is alternating 
and intermittent. The periods of flow in one direction 
should be of the shortest possible duration (^^^^^th second) . 
The flow in the opposite direction should be insufficient 
to stimulate the tissues. 

Currents of which the interruptions and reversals are 
frequent should not be applied to the body with its 
strength unvaried. If this is done, the muscles will 
be tetanised, and prolonged contraction injures them. 
The current, whatever its modification may be, should 
be made to slowly wax and wane, gradually rising 
from zero to maximum and gradually falling from 
maximum to zero. The muscles will then relax be- 
tween the contractions and their blood supply will be 
periodically replenished. 

The other tissues will also be more effectively stimulated 
if the current is made to increase and diminish slowly 
and periodically. This may be brought about by in- 
cluding in the circuit a resistance that is continually 
varying. Such a variable resistance is shown in Fig. 38. 
It consists of a cylindrical or conical glass vessel filled 
with tap-water. A vertical metal rod that leads the 
current into the water is made to rise and fall (by means 
of clockwork or a small motor) within the water in the 



RHYTHMIC VARIATION 



107 



cylinder and so interpose a column of water of varying 
length between the free end of the rod and the bottom 
of the cylinder through which the current leaves the 
vessel. Tap-water has a high resistance, so that when 
the wire is high up in the cylinder a greater length of 




Fig. 38. — Rhythmic Resistance-varying Device, Motor-driven 

water is interposed for the passage of the current. The 
current in the rest of the circuit is very weak, or stopped 
altogether. As the wire descends, so the current becomes 
stronger, and when the wire reaches the bottom of the 
cylinder the current is at its maximum strength. The 
rate at which the current rises to its maximum and falls 



io8 ESSENTIALS OF MEDICAL ELECTRICITY 



to zero can be varied, but usually the complete cycle 
{i.e. the rise to maximum and fall to zero) lasts from two 
to four seconds. 

Current regulators working on this principle are very 
useful for electro-therapeutic work. 

Another, working on the same 
principle, is shown in Fig. 39. This 
is made to fix on to the motor 
transformer of the Pantostat, so 
that the revolution of the axle of 
the motor causes the slow rise and 
fall of the metal rod in the water. 
The sinusoidal and constant cur- 
rents furnished by the Pantostat 
may thus be rhythmically varied 
in strength. 

Tap-water should be used to fill 
the glass vessel. 

Distilled water {i.e. water con- 
taining nothing in solution) wiU 
conduct the current 
scarcely at all, and 
it should contain 
just a sufficient 
amount of salt dis- 
solved, so that when 
^^^' 39 the wire rises to its 

highest position in the solution there shall be sufficient 
resistance interposed to just prevent the passage of 
current . Average tap-water contains a sufficient quantity 
of salts in solution. If more salts are added its resist- 
ance will be made too low, the current will at no period 
be cut off altogether, and there will be insufficient 
range of variation between maximum and minimum. 
If this device is used to vary a constant current, it will 
be noticed that the resistance of the tap-water rises 




SELECTION OF CURRENT 109 

higher and higher. This is because the constant current 
decomposes the salts in solution and the number of 
ions diminishes. The resistance of the water may be 
lowered by cautiously adding, a drop at a time, 10% 
salt solution. 

If there is no instrument at hand for producing 
rhythmic variation, a certain degree can be effected by 
moving one of the electrodes that convey the current 
into the body rhythmically over the skin, stroking the 
latter over the area that is to be treated, lifting it off at 
the end of each stroke. 

The question may be asked : " Which current and 
which kind of rhythmic variation is the most suitable for 
stimulating the tissues of the body ? " No definite 
answer can be given. It may be that each tissue will be 
better stimulated by one than by another. It can, how- 
ever, be said for certain that currents which rhythmically 
vary have a more effective stimulant action than those 
which are apphed without variation of strength. The 
selection will often depend upon which is available. The 
sinusoidal current rhythmically and slowly rising and 
falling between zero and maximum is particularly suit- 
able for use in baths. If the sinusoidal is not available, 
the faradic current, made to wax and wane in the same 
way, may be used. A constant current, simply inter- 
rupted by a metronome, is used by Bergonie for its 
stimulating action in the treatment of infantile paralysis. 
A slow sinusoidal current is recommended by Dr 
Reginald Morton for the stimulation of unstriped muscle. 
Mention will be made, in the chapter on treatment, 
of the form of current most suitable for the different 
diseases and morbid conditions, under their respective 
headings. 

It is possible that some of the tissues in the body are 
not stimulated or ineffectively stimulated by the methods 
at present available for applying electricity to the body. 



no ESSENTIALS OF MEDICAL ELECTRICITY 

It may be that each tissue requires its own appropriate 
electrical stimulus, regarding its strength, duration, rate 
of rise and fall, and so on. We know that striped muscle 
can respond to an extremely brief stimulus ; muscle in a 
condition in which it shows a reaction of degeneration 
requires a much less short stimulus. Involuntary muscle 
requires slow stimuU — hence the recommendation of slow 
sinusoidal currents for treatment of morbid conditions of 
the alimentary canal. 

Application to the Body. — ^When the treatment is 
apphed locally electrodes like those already described 
for ionic medication may be used. They should be of 
large size, sufhcient to cover the whole part requiring 
treatment. 

The strength of current that a patient can bear depends 
upon its density or concentration at the places where it 
enters and leaves the skin. If small electrodes are used, 
small ports of entry for the current are provided, the 
current becomes unduly concentrated in the skin, the 
sensory nerves are strongly stimulated, and much pain 
is produced, even though the underlying muscles are 
receiving little current. 

A large surface for entry of the current ensures the 
maximum current for the parts under the skin, with the 
minimum concentration or density in the skin. In other 
words, strong appHcations may be given without dis- 
comfort or pain. 

The electrodes are made of absorbent cloth, such as 
lint or folded towel, soaked in warm salt solution 
(2% is strong enough), and felt-padded metal plates, 
similarly soaked, are placed in contact with them. The 
metal plates are connected to conducting cords leading 
from the source of current. 

If rhythmic variation is to be effected by moving one 
of the electrodes over the surface, this electrode cannot, 



ELECTRIC BATHS iii 

of course, be of a size sufficient to cover the whole part 
requiring treatment. It should, however, measure three 
inches by three inches at least. 

The importance of large electrodes and good contact 
between them and the skin has been emphasised on 
previous occasions. These requirements can be most 
easily fulfilled by using water as the electrode ; the 
water is placed in a bath and the part to be treated is 
immersed in it. The appHcation of electrical currents 
in baths has special advantages. The time occupied in 
fitting pads and removing them is saved. The part can 
be kept warm if hot water is used in the bath. Water 
acts as a perfectly fitting electrode of the largest possible 
size. The use of electrical baths must be considered in 
more detail. 

Electric Baths. — These are made of porcelain or 
earthenware, or of some other insulating material, such 
as wood or fibre. They are made of sizes and shapes to 
take a single extremity, such as the hand and forearm, 
or leg and foot. Or it may be a full-length bath to take 
the whole body. The current is led into the water in the 
bath by means of a plate of carbon or metal that hangs 
from the edge of the bath and dips into the water. The 
plate and the water thus correspond to the pad electrodes 
that have hitherto been used. Now, in order to com- 
plete the circuit, we require a second electrode. If we 
are using the arm baths or foot baths, one of these may 
be used as the indifferent electrode, with one of the 
extremities immersed in the water. This is known as the 
unipolar method of applying the current, because there 
is only the one pole in each bath. With this arrange- 
ment all the current that is flowing in the circuit passes 
through the skin of the part immersed, into the limb, 
through the body and out by way of the limb in the 
indifferent bath electrode. With this arrangement. 



112 ESSENTIALS OF MEDICAL ELECTRICITY 

therefore, other parts of the body share the treatment. 
Thus, if the forearm and hand are immersed in one bath, 
the leg and foot in another, the electrical treatment will 
be given to the hand and forearm, the upper arm and 
shoulder, trunk, hip, thigh, leg and foot. The skin of the 
parts that are not immersed will not receive much 
current, because the latter, having traversed it in the 
immersed parts, keeps to the underlying parts, as the 
resistance of the latter is low and that of the skin high. 

With the arrangement described, electrical treatment 
may be given to any two of the extremities simul- 
taneously. The trunk does not receive much stimulation, 
as it is the widest part of the circuit, and so the current 
density is low. 

If it be desired to treat the four extremities simul- 
taneously, two more baths are provided, to take the 
other limbs. The current can be sent from any two to 
the remaining two, or from any one to one or more of the 
remaining three. When the four extremities are receiv- 
ing treatment simultaneously the trunk receives more 
stimulation, so that the whole body except the head 
can receive electrical treatment by this arrangement. 

The Schnee bath is an arrangement of four baths, 
one for each extremity. It is shown in Fig. 40. By its 
means the current may be applied to two or more of the 
extremities, the trunk sharing it to a greater or lesser 
extent. The Schnee bath is useful for appl5dng the 
electrical current to the whole body. There is, however, 
no stimulation of the skin except that of the parts 
immersed. 

A switch-board is suppHed with the Schnee bath out- 
fit, so that the current that is available can be directed 
between any two, or more, of the baths. Either the 
faradic or the constant or the sinusoidal may be 
used. 

In the case of the full-length bath, both electrodes are 



SCHNEE BATH 



113 



immersed in the water, one at either end. The current 
passes between the electrodes and travels partly through 
the water, partly through the body. 




Fig. 40. — Schnee Bath 

The Full-length Bath.— As a means of applying elec- 
tricity to the whole body the electric bath is the most 
agreeable and most efficient method we have. Large 
electrodes are placed at the head and foot, and the bath 



114 ESSENTIALS OF MEDICAL ELECTRICITY 

filled with water at a temperature of from 98° to 100° 
Fahr., so as to cover the patient's shoulders when he is in. 
The electrodes should be of metal and kept clean and 
bright. They should be 12'' x 18" for the head, and 
\z" X lo'' for the foot. A paddle electrode (Fig. 41) 
connected to one of the others is sometimes used by the 
operator to concentrate the current on any required 
part. It consists of a plate of metal, 4 inches square, 
mounted on the end of a long handle. It is connected to 
one of the other electrodes or it may replace it. A back 
rest made of a wooden frame with strips of webbing 
stretched across is required for the patient to lean 
against, and keep him from contact with the electrode. 
A similar one is not required for the foot. They should 




Fig. 41.— Paddle Electrode 

be made to fit the bath in which they are used or they 
will give trouble. 

The full-length bath is a " bipolar " bath, as both 
electrodes are immersed in the water. The current will 
pass through the water from pole to pole, and some of it 
will pass through the body, the relative amounts depend- 
ing on the resistance of the body and the resistance of the 
surrounding water. If there is much surrounding water, 
its resistance will be less than if there is a smaller quantity, 
and a greater share of the current will be taken by the 
water, leaving less for the patient. If salt were added to 
the water the resistance of the latter would be much 
lower and still less current would pass through to 
the patient. The amount of current passing through 
the patient is not the same in all parts of the body ; the 
thick trunk has a smaller resistance than the narrower 
limbs, so that the former will take more of the current 
than the latter. 



APPLICATION OF ELECTRIC BATH 115 

The full-length bath allows a greater general stimula- 
tion of the body than the Schnee bath, because in the 
latter only portions of the skin are immersed, whereas in 
the former the whole body is immersed. By means of 
the full-length bath it is possible to administer the largest 
quantity of electricity to the body, because the current is 
provided with the largest possible area of entry. 

Current for Use in the Bath. — ^For the purpose of 
general stimulation of the body a valuable current is the 
sinusoidal. It should be applied so that it slowly and 
rhythmically varies in strength as it passes through the 
patient. The current may be taken from the main, 
using a static transformer when the main current is 
alternating or a motor transformer when it is direct. If 
there is no main supply at hand, the current from a 
battery of accumulators may be taken to the motor 
transformer. An alternative method is to use the farad ic 
current, also rhythmically varied. The direct current 
from the main simply interrupted or simply reversed, as 
described on page 18, should never be sent directly 
through the bath, on account of the risks mentioned on 
page 52. 

How the Electric Bath is given. — ^The bath should be 
filled with warm water at 99° or 100°, as measured by a 
thermometer, to a height sufficient to cover the shoulders. 
The wire connections should be tested to see that they 
are not loose and then the current is turned on to half 
strength. The operator should place his hands in the 
water so as to be sure that the current is flowing. The 
current is then reduced to zero again. The patient then 
enters the bath, and the current is gradually increased, 
Httle by little, till no more can be borne without dis- 
comfort. After ten to twenty minutes the current should 
be gradually reduced to zero, as before. 



ii6 ESSENTIALS OF MEDICAL ELECTRICITY 

If languor or depression follows the bath it may mean 
that the current has been too strong, but some degree 
of fatigue is customary after an electric bath. It is 
temporary, and the patient should be forewarned of its 
likeHhood. The patient should dress slowly, so as to cool 
off gradually, and rest for a quarter of an hour or so before 
going out into the open air. There is no special liability 
to catch cold after an electric bath, particularly if the 
patient walks home, which he should always do if 
possible. 

At least twelve baths are required to produce a satis- 
factory result — but many cases arise in which it is found 
necessary to give a great many more. In no form of 
electrical treatment is it more necessary to exercise the 
utmost care than in everything pertaining to the electric 
bath ; what would be of more or less trivial account 
under other conditions becomes a serious matter here. 
Any sudden change in the magnitude of the current, 
however small, has a very alarming effect on the patient. 
This is not unreasonable, considering how helpless he is 
when immersed in the water, and so placed that small 
changes have as much effect as large ones under other 
circumstances. Binding screws, conducting cords and 
the slider of the regulating resistance are all sources of 
trouble. They should be frequently inspected and 
tested, and all the apparatus should be personally 
examined by the medical man before each bath is given. 
He should turn the current on himself and not leave the 
room until he has turned it off, before the patient comes 
out. For female patients a bathing dress is necessary, 
as is also the presence of a nurse or maid in the room. 
The electric bath is a most valuable method of applica- 
tion ; as a means of " general electrisation " it is the 
best at our disposal, and one of the most frequently used 
in this country. In America, " general faradisation " is 
the more popular method, and the electric bath is 



FARADISATION— GALVANISATION 117 

apparently used to only a limited extent. This is a 
striking instance of the difference in the usual practice 
of the two countries. 

General Faradisation or Galvanisation. — ^In the absence 
of an electric bath there is another method of bringing 
the whole body under the influence of the stimulating 
action of the electrical current. 

This method is very fuUy described and illustrated by 
RockweU, of New York, in the last edition of his work. 
The patient stands or sits on a large metal plate, which is 
covered with moist flannel, and if necessary kept warm 
by a hot-water bottle. One wire from the induction coil 
is attached to this plate, and the other to the active 
electrode. The latter may be a felt-covered metal plate 
with a handle attached for the operator. Sponge may 
be attached to the felt. It is moved over the head, 
neck, back, abdomen, arms and legs — ^from two to three 
minutes being given to each. The strength of current 
is not so strong as to be the least impleasant. A 
pleasant feehng of vigour foUows, with rehef of fatigue 
and improved appetite and abihty to sleep. There is 
no doubt as to the great value of the method, and it is 
the one to employ whenever the electric bath is not 
available. 

The faradic current may be used alone or in combina- 
tion with the constant current. This was suggested 
by Dr de Watteville and the treatment was called by 
him " galvano -faradisation." 



CHAPTER IX 

ELECTRICAL TREATMENT OF PARALYSIS 

Electricity is a valuable agent for the treatment of 
paralysis and will, in suitable cases, give results that 
cannot be obtained by other methods. It is, however, 
of the first importance that correct methods of appHca- 
tion should be employed, and it is the failure to recognise 
and adopt them that is generally responsible for the 
inability to obtain good results and the scepticism that 
still prevails in some quarters regarding the value of the 
treatment. 

In any case of paralysis we have to consider, for the 
purpose of electrical treatment, the muscles, their nerves 
of supply, other tissues that are secondarily affected, 
and the cause that is responsible for the paralysis. In 
cases where the cause is irremovable and progressive, as, 
for example, in progressive muscular atrophy, paralysis 
agitans, etc., the degenerative changes in the nerves and 
the atrophy of the muscles will proceed and little can be 
expected from electrical treatment. But in cases where 
the cause can be removed or has ceased to operate, the 
nerves will recover their function, or regenerate, if their 
motor nerve cells have not been destroyed. 

Nerves recover their function slowly, especially if 
regeneration has to take place. During this period the 
muscle is not only out of use, but under conditions that 
impair its nutrition and that of its nerves and its sur- 
rounding parts. By suitable electrical treatment the 
muscle can be exercised and the condition of the sur- 
roxmding parts ameUorated. The changes that take 

ii8 



CHANGES OCCURRING IN PARALYSIS 119 

place in a paralysed limb may be briefly considered, 
together with the way in which electrical treatment pro- 
duces beneficial results. When a muscle is paralysed 
as a result of injury or disease of its nerve (lower motor 
neuron) the following changes take place and persist till 
the nerve has recovered its function. 

The muscle ceases all work. It is not even a resting 
muscle, for there is some degree of continuous contraction 
or tone in a resting muscle, and chemical changes are still 
going on in it. But when there is a lesion of the lower 
motor neuron, the muscle ceases work entirely. It hangs 
loosely from its extremities, supported by the skin. 
Its circulation becomes feeble in the extreme, and the 
blood supply to the adjoining parts is much impaired. 
The temperature is lowered and the muscle cannot 
shiver itself warm. The skin becomes blue and cold, 
and chilblains develop. The growth of the bone is 
retarded. 

If the nerve fibres regenerate there may be some 
recovery of function by the muscle, but less in propor- 
tion to the length of time during which the muscle has 
remained in this abnormal condition. 

When the lesion causing the paralysis is in the upper 
motor neuron the condition is less bad when the muscles 
have passed into a spastic condition, for then there is 
increased tone, and chemical changes continue, and the 
circulation is not so impaired. But the muscle cannot 
contract and its fibres may be to some degree replaced by 
fibrous tissue as a result of loss of active use, before 
voluntary power returns. And during the time before 
the muscles pass into the spastic state their condition is 
that of muscles in flaccid paralysis. 

To prevent these changes a proper circulation must be 
maintained in the limb, and the muscles and nerves must 
be artificially stimulated so as to make them work and 
improve their blood supply. No method of treatment 



120 ESSENTIALS OF MEDICAL ELECTRICITY 

can bring this about more effectively than electrical 
currents properly applied in the way to be described. 
Every part is traversed by the current, and every nerve 
fibre and muscle fibre is stimulated, while all the tissues 
benefit from the improved blood supply. 

The points to which attention should be particularly 
directed when giving electrical treatment may be con- 
sidered in order. 

The Current to be used. — ^The use of an unmodified 
constant current produces but little stimulation, as 
shown by the experiments of Debedat (page 121). The 
current must therefore be modified, so as to bring about 
the most effective stimulation of the tissues. 

It is commonly taught that if the paralysed muscles 
show normal reaction the faradic current {i.e. the current 
from an induction coil) should be used, while if they show 
the reaction of degeneration, the galvanic current should 
be used. This choice of current is probably based on 
theoretical grounds. Since the times of Duchenne and 
Remak, each current has been regarded as superior to 
the other by different observers. The galvanic is the 
only current that wiU cause contraction of a muscle 
showing the reaction of degeneration, but it has to be 
proved that it is necessary to cause muscles to contract 
when treating them for paralysis. It is possible that 
one current may be more suitable for some tissues in 
cases of paralysis, another current for others. 

Whichever current be chosen, it is essential that it 
should be continually var3dng in strength. Var3dng 
currents have a greater stimulating action on the tissues 
than steady currents and increase their metabolism to 
a greater extent. A constant current, unvarying in 
strength, such as is so commonly supplied to baths, has 
little or no value in the treatment of paralysed muscles. 
A faradic current, unvarying in strength, tet anises, 



RHYTHMIC VARIATION OF CURRENTS 121 

fatigues and asphyxiates the muscles (if they respond 
to this current), and does actual harm. 

Some experiments were carried out by Debedat to 
determine the influence on growing muscles of different 
electrical currents applied in different ways. It was 
found that the rhythmically varied faradic current 
caused the largest growth (40%) ; the rhythmically 
varied galvanic current caused an increase by 18%. 
These currents were both allowed to flow, during each 
application, intermittently, periods of flow and periods 
of rest alternating, each lasting for one second. If 
the currents flowed continuously without rhythmic 
variation, quite different results were obtained. The 
muscles treated by the unvarying galvanic current 
showed but a slight increase in size ; those treated by the 
faradic current with strength unvaried, diminished in 
size and the muscle fibres were damaged, as shown by 
microscopic examination. 

These experiments show the importance of rh3d:hmic 
variation in the strength of the currents used for their 
influence on growing tissues, and it is reasonable to 
conclude that rhythmically varying currents are more 
effective in the stimulation of paralysed muscles and 
nerves— a fact which is borne out by clinical experience. 

The modifications and variations of the electric current 
are described in Chapter II., and are summarised in 
Chapter VIII. It is a very difficult task to decide which 
of these is the best. If the choice lies between the 
faradic and galvanic, we may select the galvanic current 
for treatment of muscles showing the reaction of de- 
generation, and the faradic current for muscles showing 
reactions of the normal type. 

When the faradic current is used it should be made to 
vary its strength by the water resistance method (page 
106). Or it may be sent through a metronome in- 
terrupter, which is made to swing so that the current 



122 ESSENTIALS OF MEDICAL ELECTRICITY 

flows for periods of one second each, followed by a period 
of rest of equal length. The metronome interrupter 
produces sudden contractions, while the water resistance 
produces gradual contractions. The latter are more 
pleasant. 

When the constant current is used it should be in- 
terrupted periodically by the metronome (simple inter- 
mittent current), so that periods of flow and no-flow 
follow one another, each lasting one second. 

The sinusoidal current is very valuable in the treat- 
ment of paralysis. Not only does it produce good results, 
whether the muscles show the reaction of degeneration or 
normal reactions, but it is the simplest to use, and when 
appHed to arm or foot baths or full-length baths very 
little attention is required. The sinusoidal current is 
appHed to eight baths in the electrical department at 
St Bartholomew's Hospital. 

When no device for rhythmic interruption or variation 
is available the effects may in some degree be produced 
by moving one of the electrodes to and fro and on and 
off the skin. 

The Electrodes. — ^These are of the same design as 
those previously described, pads of folded lint or towel, 
covered by felt and metal plate (Fig. 33). They should 
be large enough to cover the group of muscles requiring 
treatment. When the rh3^hmic variation has to be 
effected by moving one of the electrodes over the skin, 
this electrode cannot be of a large size ; it should, how- 
ever, measure at least three inches by three inches. The 
small padded disc or button so frequently suppUed in the 
induction coil cases should not be used, as they are much 
too small. Only a small current can be appHed through 
small electrodes, and the attempt to use a current of 
adequate strength will cause unnecessary pain. 

The use of small electrodes in the treatment of paralysis 



SITUATION OF ELECTRODES 123 

in children is responsible for the statement that electrical 
treatment of infantile paralysis is impracticable on 
account of the pain which it produces. 

When the paralysis is general, or when it involves an 
extremity, the best electrode is water — ^in the Schnee 
bath or full-length bath, because the largest current can 
be given with the least amount of sensation. The parts 
immersed are kept warm, they are surrounded by the 
water, which acts as a perfectly fitting electrode, and 
the time that would be occupied by applying the usual 
electrodes is saved. This saving of time is matter for 
consideration in hospital practice. 

If the lower limbs are to be treated, the full-length 
bath may be used, the patient sitting up, with only the 
lower limbs and pelvis immersed. In the case of the upper 
limbs and shoulders the Schnee bath (page 112) may be 
used. The Schnee bath may also be used for the lower 
limbs and also for the whole body. 

With regard to the situation of the electrodes, they 
should be placed so as to include in the part traversed by 
the current, not only the affected muscles, but also the 
affected nerves, and, when possible, the cause that is 
responsible for the paralysis. Thus, for example, in 
paralysis of the extensors of the upper limb caused by 
pressure or other injury to the musculo-spiral nerve, one 
electrode should cover the posterior aspect of the fore- 
arm, and the other should be placed around the upper 
arm and shouldei;, so as to cover the region of the injury. 
Or when the Schnee bath is used the.opposite arm should 
be immersed in the other arm bath, so that the current, 
on its passage from bath to bath, wiU traverse the seat of 
the injury. 

The situation of the electrodes will vary in each case, 
according to the part paralysed, and the cause responsible, 
and the matter will be further considered under the head- 
ings of paralysis of different regions. 



124 ESSENTIALS OF MEDICAL ELECTRICITY 

The Strength of the Current and the Duration of the 
Treatment. — ^At the present day stronger applications are 
made and the duration and frequency are increased, and 
evidence goes to show that better results are obtained. 
Bergonie has increased the length and strength of the 
electrical treatment of infantile paralysis, and he now 
gives two applications daily, each lasting thirty to sixty 
minutes. No fatigue occurs, and nothing but good 
results. In busy hospital practice, treatment cannot be 
given so frequently, as a rule, and two applications each 
week, lasting for thirty minutes each, may be given to 
out-patients. In private practice the consideration of 
expense will sometimes prevent a patient coming for 
treatment with sufficient frequency. Under these 
circumstances it may be advisable for the patient to 
receive treatment in his own home, where it may be 
given by a nurse or by one of his relatives or even by him- 
self, under instruction and supervision by his doctor. 
The faradic current may be used, and an induction is the 
least expensive to buy. The galvanic current, from a 
portable battery, may be used, but the apparatus costs 
more. Portable batteries may sometimes be had on 
hire. Whichever current is used, it should be appUed 
with its strength rhythmically varied, and the readiest 
way for the patient to do this is to use a movable 
electrode in the way previously described. Home treat- 
ment may be given for fifteen minutes twice daily. 

Treatment of Peripheral Nerve Paralysis. — In this 
chapter will be considered the electrical treatment of 
paralysis due to lesions of the peripheral nerves, and 
to anterior poliomyeUtis in children. The treatment of 
paralysis due to diseases of the central nervous system 
will be found in Chapter XIV. 

The value of electricity in hastening recovery after 
injury or disease of the peripheral nerves is now very 



PERIPHERAL NERVE PARALYSIS 125 

generally accepted. Though it is maintained by some 
that the cases would recover quite as rapidly without 
treatment, many arise which remain stationary for a 
considerable period of time before electricity is appHed, 
and then begin to improve rapidly. 

The paralysis may be due either to injury or disease of 
the nerve. Injury of the nerve trunks are most common 
in those placed superficially, and the injury may be of 
any degree varying between slight pressure, causing 
numbness, to bruising, laceration and division, with loss 
of motor power and sensation in the localities supplied 
by the nerve or nerves implicated. 

They occur more often in the shoulder and arm, and 
all cases are most interesting from the diagnostic stand- 
point. Falls, blows, dislocations, pressure as from the 
use of a crutch, or falling asleep with the arm over the 
back of a chair may produce a musculo-spiral paralysis. 
Incised wounds about the wrists from broken glass or 
other cause frequently result in division of the ulnar or 
median nerves. The first thing to be done in any case 
of division is to find and suture the divided ends — or 
if the paralysis is the result of pressure by cicatrical 
tissue or callus it must be freed from its surroundings. 
The case will be referred for electrical treatment at 
a later date, and if tested, reaction of degeneration 
will be found in the muscles supplied by the injured 
nerve. 

The paralysis may be due to disease of the peripheral 
nerves. Alcohol, metallic poisons (such as lead and 
arsenic), gout, syphilis, sepsis and the specific fevers are 
common causes. Often there is no discovered cause and 
we speak of a " rheumatic " neuritis. If a mixed nerve 
is affected, either by disease or injury, pain may be 
severe, or, on the other hand, it may be slight or absent. 
If pain is present it is a good plan to commence the 
treatment by ionising the painful regions with salicylic 



126 ESSENTIALS OF MEDICAL ELECTRICITY 

ions, and leaving the usual treatment till the pain has 
subsided or lessened. 

Facial Paralysis. — ^The cases that respond best to 
electrical treatment are those in which the paralysis is 
due to simple inflammation and swelling of the nerve 
trunk — cases of Bell's palsy. Here the exciting cause 
of the neuritis, whatever it may be, disappears in a 
majority of cases, or ceases to act, and we are left with 
the damaged nerves and paralysed muscles. The treat- 
ment may be carried out in the following way : — If the 
muscles show the reaction of degeneration, the constant 
(galvanic) current is to be used. One electrode is con- 
nected to the positive pole of the source of current. The 
hand is placed in contact with it. This is the " in- 
different " electrode. The active electrode, made of a 
metal disc, two inches in diameter, padded with felt 
(of the same kind as that described and illustrated 
on pp. 140, 141), is soaked in a 2% solution of sodium 
salicylate and connected to the negative pole of the 
source of current. It is then stroked across the face, and 
at the same time the current should be turned on and 
increased till it is as strong as can be borne. The elec- 
trode should be stroked across the face successively over 
the main branches of the nerve starting behind and below 
the pinna (from the region where the nerve leaves the 
stylo-mastoid foramen) and ending at the middle line of 
the face. Here the electrode should be lifted off the skin, 
so as to interrupt the current, and then be replaced over 
the foramen and again stroked across the face. 

The stroking action causes variation in the strength of 
the current and stimulation of the muscles and nerve. 
Salicylic ions migrate through the skin, and they may 
have a beneficial influence on the inflamed nerve and, 
possibly, some action on the agent responsible for the 
neuritis, if this be some micro-organism. 



TREATMENT OF FACIAL PALSY 127 

Another method of treatment is to cover the whole 
of the affected side of the face with a pad, cut to the 
correct shape, and soaked in 1% saUcylate of soda. 
This pad is connected to the negative pole and secured 
to the face. By placing a rhythmically varying resistance 
in circuit the current is made to wax and wane, or is 
suddenly interrupted and resumed. 

The first method is the simplest and is easier to apply. 
The treatment should be given at least twice each week, 
and for twenty minutes each session. It may be given 
more frequently — every other day, or even daily if 
there is no erythema or tenderness remaining from the 
previous treatment. 

If the facial muscles do not show the reaction of 
degeneration, the faradic current will be sufficient. It 
can be applied in the same way. The active electrode 
is soaked in dilute salt solution. A dry wire metal 
brush may be used instead of the moistened padded disc, 
and stroked over the dry skin. This produces strong 
sensory stimulation of the skin of the face and influences 
the facial nerve and its muscles reflexly. 

Cases of facial paralysis due to inflammation spreading 
to the nerve from the middle ear will not be improved 
until the latter region has received appropriate treatment. 
Electrical treatment is less likely to produce favourable 
results in these cases. 

Facial paralysis due to a lesion in the upper motor 
neuron is more likely to recover spontaneously than those 
in which the lower neuron is involved. 

Paralysis of the Shoulder Muscles, — The trapezius and 
sterno-mastoid are frequently paralysed, either singly or 
both together. To carry out electrical treatment when 
the trapezius or when both muscles are paralysed, one 
electrode should be fixed in the posterior triangle of the 
neck, overlapping the sterno-mastoid when this muscle 



128 ESSENTIALS OF MEDICAL ELECTRICITY 

is also paralysed. The other electrode, a metal disc 
three inches in diameter, padded with felt, should be 
stroked over the trapezius from insertion to origin, 
passing, in order, over different parts of the muscle. The 
electrode on the neck overlies the spinal accessory nerve, 
so that the latter is included in the treatment. 

When the paralysis involves the sterno-mastoid alone, 
an indifferent electrode may be placed on the back, while 
the active electrode may be stroked along the muscle and 
nerve. 

When the paralysis is due to a simple neuritis of the 
spinal accessory nerve, the electrode overlying the nerve 
may be soaked in i% salicylate solution and connected 
to the negative pole. The other electrode is then 
soaked in salt solution. When the paralysis is due to 
inflammation spreading to the nerve from suppurating 
tuberculous glands, the latter must receive treatment 
before electrical treatment of the muscles can be carried 
out with any prospect of success. When due to injury 
of the nerve, similar methods may be employed, but the 
nerve, if it has been accidentally divided during surgical 
operation, must be sutured. When due to spinal polio- 
myelitis, similar treatment may be given on the chance 
that some part of the nucleus of origin of the nerve has 
escaped destruction. 

Serratus Magnus. — Paralysis of this muscle may result 
from injury to the posterior thoracic nerve as a result 
of blows on the side of the neck or an injury to the 
shoulder region. It may be the result of neuritis. For 
electrical treatment one pad should be fixed in the 
posterior triangle. The other should be stroked over 
the serrations of the muscle. 

The Deltoid. — ^Many cases of paralysis of the muscle 
are encountered. The paralysis may be the result of 
blows on the shoulder causing injury to the circumflex 
nerve in its course through the muscle. Or the nerve 



TREATMENT OF DELTOID PARALYSIS 129 

trunk may be compressed by pressure within the axilla 
caused, e.g., by a crutch-head, or by injury or dislocation 
of the shoulder. The teres minor is paralysed with the 
deltoid when the injury involves the nerve trunk before 
it enters the muscle. 

For electrical treatment of the paralysed deltoid, it is 
advisable, when the paralysis is due to injury, and the 
injury is recent, to surround the limb in the region of the 
injury by one electrode, place the other electrode around 
the forearm and direct the galvanic and afterwards the 
faradic or sinusoidal currents between the two electrodes, 
rhj^hmically varying in their strength by means of the 
instrument described on page 106. The galvanic current 
will probably have some action in helping the absorption 
of effusions into the region of the injury. Afterwards 
the sinusoidal or faradic current may be used. It may 
be applied in the Schnee bath, the arms immersed in 
their respective vessels. Another method is to immerse 
the forearm of the affected side in the Schnee bath and 
to apply the other electrode to the shoulder, fixing it 
there, or using a movable electrode and stroking it over 
the region of the muscle. In the latter method, no 
rhythmic current regulator is needed. 

The Spinati. — Of the other shoulder muscles, the 
spinati are more frequently found paralysed than the 
latissimus dorsi, pectorales, teres major and subscapu- 
laris which usually escape. The spinati are paralysed as 
a result, usually, of injury of the suprascapular nerve. 
Electrical treatment is carried out by fixing one electrode, 
connected to one pole, in the posterior triangle ; the other 
electrode may be moved over the affected muscles. The 
spinati are frequently paralysed with the deltoid. 

Paralysis of the Arm Muscles. — ^The muscles supplied 
by the musculo-spiral nerve and its branches (triceps, 
brachio-radiaUs, supinator brevis and the extensors of the 
I 



130 ESSENTIALS OF MEDICAL ELECTRICITY 

wrist, fingers and thumb) may be paralysed as the result 
of injury or of disease of the nerve. The injury may result 
from dislocation of the head of the humerus, in which 
case other nerve trunks may be injured as well, or it may 
result from fracture of the humerus or involvement of the 
nerves in the callus. The triceps will escape if the nerve 
trunk is injured below the origin of the branches to this 
muscle. The nerve trunk may be damaged by pressure 
from a crutch-head or the back of a chair. 

Apart from injury, the muscles may be paralysed from 
neuritis. Chronic lead poisoning and alcoholic excess 
are the common causes of this neuritis. The triceps 
usually escape, leaving the forearm muscles paralysed, 
so that wrist-drop is produced. In lead poisoning the 
brachio-radialis is said to escape. 

Before electrical treatment is commenced the cause of 
the paralysis must be removed wherever possible. For 
the treatment one electrode is placed on the shoulder, 
the other on the posterior aspect of the forearm. The 
paralysed muscles should be supported by a spUnt applied 
to the anterior aspect of the forearm, so as to prevent 
their extension by the antagonistic muscles. The splint 
should also be worn between the sessions of treatment. 

An alternative method is to use the Schnee bath and 
direct the current from arm to arm. 

The conmion causes of paralysis of the muscles supplied 
by the ulnar and median nerves are injury in the region 
of the elbow, or shoulder, or wrist. The injury may be a 
dislocation of the joint or fracture in its region : other 
nerve trunks in the neighbourhood may be simultaneously 
injured. In the region of the wrist an incised wound is 
the common cause. Pressure from a crutch-head may 
also injure the ulnar nerve as well as the musculo-spiral. 
A cervical rib may cause pressure on the first dorsal nerve 
root. In this root run some of the fibres that ultimately 
go to form the ulnar and median nerves ; ulnar and 



PARALYSIS OF MEDIAN AND ULNAR 131 

median paralysis may therefore be caused by pressure 
from a cervical rib. The intrinsic muscles of the hand 
are usually affected : sometimes also the forearm muscles 
supplied by the nerves mentioned. 

Injury or disease of the ulnar nerve results in loss of 
power, wasting and, often, reaction of degeneration in 
flexor carpi ulnaris, flexor profundus digitorum (inner 
half), the hypothenar eminence, all the interossei, two 
inner lumbricales, adductor pollicis and inner head of the 
flexor brevis pollicis. Later on the proximal phalanges 
become over-extended, and the distal phalanges flexed, 
due to the unopposed action of the long flexors and 
extensors. The hand becomes thin and flat, and the 
characteristic deformity known as the claw hand is pro- 
duced. There is also loss of sensation in the little 
finger, ulnar half of the ring finger, and correspond- 
ing part of the palm. 

The rnedian nerve is sometimes divided at the same 
time as the ulnar. If injured or diseased there is paralysis, 
wasting and, often, reaction of degeneration in the 
abductor poUicis, opponens pollicis, and outer head of 
the flexor brevis poUicis. 

There is wasting of the thenar eminence, and the 
thumb is everted with the nail facing dorsally. Sensa- 
tion is lost in thumb, index and middle fingers and half of 
the ring finger and corresponding part of the palm. These 
are the events that follow a lesion of the median nerve in 
the region of the wrist. When the nerve trunk is injured 
or diseased in the forearm or higher up, the flexors of the 
fingers and thumb, radial flexor of the wrist, palmaris 
longus and pronators are paralysed in addition. The 
treatment of paralysis of the median and ulnar nerves is 
carried out on the same lines as that of the musculo- 
spiral. 

Erb's Paralysis. — Cases of paralysis of a group of 



132 ESSENTIALS OF MEDICAL ELECTRICITY 

muscles which does not correspond to the distribution 
of any single nerve trunk are not uncommon. In these 
the lesion will be found very often in the nerve root as it 
comes from the spine and before it reaches the plexus. 
This is known as " root paralysis." If the muscles 
suppHed from the different nerve roots are known, the 
operator wiU easily manage to refer them to their proper 
origin. One of the most common of these is that known 
as Erb's paralysis. It results from disease or injury of 
the fifth and sixth cervical roots before they join the 
brachial plexus. The muscles affected are the deltoid, 
biceps, coraco-brachialis, brachialis-anticus and brachio- 
radialis. 

All these muscles are thrown into action in the normal 
subject by stimulation of Erb's point (see Plate I.). 

It will be also noticed that three nerve trunks are 
represented in the above-mentioned group of muscles — 
viz. the circumflex supplying the deltoid, the musculo- 
cutaneous supplying the coraco-brachialis, brachialis- 
anticus and biceps and the musculo -spiral suppl3dng the 
brachio-radialis. The position of the arm and hand in 
this condition is very characteristic. The arm hangs 
straight down by the side, and the hand is rotated in- 
wards, so that the palm is looking backwards. It has 
been humorously referred to as the " policeman's tip " 
position, which is a fairly accurate description of it. It 
has also been called " obstetrical " palsy, as it has 
often resulted from traction on the arm in difficult 
labour. 

The prognosis in any case depends on the nature and 
severity of the lesion producing it. If due to pressure 
and involvement by malignant disease it would, of 
course, be very unfavourable. If due to injury at birth 
the extent of the injury wiU determine the nature of 
the prognosis. In severe cases where the nerves are 
lacerated or torn out from the cord recovery is practic- 



TREATMENT OF ERB'S PALSY 133 

ally impossible. Most cases fortunately are less severe 
than this, and recovery to a greater or less extent is 
the rule. 

It will be assisted and hastened by electrical treatment. 
Treatment must be kept up regularly and persistently 
so long as improvement continues. 

One electrode should be fixed to the posterior aspect of 
the neck, so as to cover the cervical enlargement. The 
other should be stroked over the shoulder, anterior aspect 
of the arm and radial border of the forearm. 

The mother or nurse should be instructed to massage 
the arm once or twice daily for from five to ten minutes 
at a time, and, while doing so, to hold the limb so as to 
correct the faulty position. It is also advisable to pro- 
tect the arm from cold as far as possible, especially in 
the winter months. 

It is important to remember that great care is to be 
taken in dealing with children, so as not to frighten them 
by using too strong a current at the beginning. Indeed 
it is a good rule at the first application not to turn on any 
current at all, but to have everything else arranged as 
usual. This gains the child's confidence, and at the next 
application a very mild current is used. This is gradually 
increased on subsequent occasions until a sufficiently 
strong current is applied. 

Peripheral Nerve Paralysis in the Lower Limb is much 
less common than in the upper extremity. It may be 
caused by injury in the region of the knee joint or pene- 
trating wounds of the sciatic nerve. A neuritis of the 
sciatic nerve trunk or of its cords of origin may be 
the exciting cause. 

The electrical treatment is carried out on the same 
lines as for paralysis in the upper limb. The full-length 
bath is very convenient. The Schnee bath is also useful. 
If there is foot-droop, a support should be worn so as 



134 ESSENTIALS OF MEDICAL ELECTRICITY 

to prevent passive stretching of the paralysed muscles. 
In the Schnee bath the support may be effected by 
resting the sole of the foot on the bottom of the bath with 
the leg vertical. In the full-length bath the foot may be 
pressed against the vertical metal electrode at the foot 
of the bath. 

In cases of paralysis of the sciatic nerve where the 
onset is sudden with much acute pain, the treatment 
should be commenced by ionisation of the nerve with 
salicylate. When the pain is subsiding, the treatment 
may be changed to application of the sinusoidal current, 
rhythmically varied, in the long bath. 

Treatment of. Infantile Paralysis. — ^This is the most 
common form of paralysis met with in the electrical 
department of a hospital, and fortunately is one for 
which a great deal can be done. The seat of the disease 
is in the anterior cornu of the spinal cord, where a more or 
less extensive destruction of the ganglion cells is found. 
Owing to the fact that the nucleus of origin of the motor 
nerve of any muscle extends through one or more 
segments of the cord, it is impossible for any locaUsed 
lesion to paralyse any single muscle exclusively, and also, 
especially if the lesion is smaU, it is unlikely that any large 
muscle will be completely deprived of the influence of the 
nucleus of origin of the nerve which supplies it. Part of 
its nucleus may be destroyed, while other parts are less 
damaged or even uninjured. 

The teaching that the ganglion cells are either destroyed 
or uninjured — ^rendering treatment futile in the one case 
and unnecessary in the other — is incorrect and harmful. 
The experience, extending over some years, obtained in 
the Electrical Department at St Bartholomew's Hospital 
is a direct refutation of it. No case is so extensive or 
so severe that no good will result from proper and 
persistent treatment. 



TREATMENT OF INFANTILE PARALYSIS 135 

The state of the muscles in any case will depend on the 
severity of the original attack and on the time that has 
elapsed before coming for electrical treatment. It may 
vary from slight weakness without wasting or loss of 
voluntary power to complete paralysis with wasting and 
loss of response to all electrical or other stimuli. Differ- 
ent degrees may be found in the same case, and while the 
milder cases tend towards spontaneous recovery, it may 
be safely claimed that without electrical treatment the 
recovery is slower and less complete. In the more 
severe cases where there is wasting and reaction of 
degeneration, the tendency to spontaneous recovery is 
very slight, but here electricity is able to do a great deal 
to improve matters. 

When the lower limbs are affected, as is usually the case, 
the treatment may be carried out in one of two ways. 
In one, the patient is immersed in warm water in a bath 
of suitable size. The current may be either a faradic or 
a sinusoidal ; both must be rhythmically varied. The 
weakest application must be made during the first 
session, and stronger applications should be made 
subsequently. It is very important that the child should 
not receive strong applications at the beginning of the 
treatment, when it is unused to it. The application of 
the treatment in baths is the pleasantest way and 
children will rarely cry when they are receiving it. 
There are two baths in the Electrical Department 
of St Bartholomew's Hospital for the treatment of 
infantile paralysis. The mothers bring their children up 
with great regularity, and the good results that follow 
correctly applied electrical treatment are seen. 

When treatment is commenced chilblains, if present, 
disappear, the skin loses its blue colour and the limb 
becomes warm, even though, at this stage, no voluntary 
power of the muscles may have been regained. If 
the anterior horn grey matter has not been damaged 



136 ESSENTIALS OF MEDICAL ELECTRICITY 

beyond repair, some voluntary power will be recovered 
and reactions of the normal type wiU return. 

The best results are seen in hospital practice, where 
question of expense does not arise to cut short what is 
always a long course of treatment. Where expense has 
to be considered, an electric bath may be improvised for 
home treatment from a wooden tub or earthenware foot 
bath. It is filled with water, and a current from an in- 
duction coil is sent through the water by way of two 
metal plates, one placed at each end of the bath. 
Rhythmic variation can be effected by slowly sliding the 
secondary coil over the primary or pulling the metal 
sleeve slowly backwards and forwards over the iron core. 

This may be carried out at home and the mother or 
nurse instructed in all the details of the treatment, but 
where possible some part of the treatment should be 
carried out by the medical man, as this ensures thorough- 
ness in at least part of the treatment, and also makes 
it more easy to keep in touch with the progress of the 
case. 

Another method of electrical treatment of infantile 
paralysis of the lower limbs is used by Bergonie. One 
electrode, in the form of a large, well-fitting pad 
moistened with warm saline, is placed under the back. 
The other is wrapped round the soles and the rest of the 
feet. The faradic current is used when the muscles show 
reactions of the normal type ; the galvanic current 
when there is reaction of degeneration. Either current 
is interrupted rhythmically by a mercury metronome. 

Massage and manipulation constitute a useful acces- 
sory treatment. It is a mistake to say that massage can 
replace properly applied electrical treatment and procure 
equally good results. This is particularly true in refer- 
ence to cases showing blueness of the skin, with chilblain 
and ulcers. The application of the electrical treatment 
in the bath causes their prompt disappearance, while 



DURATION OF TREATMENT 137 

massage is generally ineffective for this condition of the 
skin. 

The objection is raised that the electrical treatment 
stimulates the antagonist muscles (if they are healthy) 
to contract, so that those which are paralysed are 
passively stretched. This can be avoided by applying a 
suitable spUnt so as to support and fix the part moved by 
these muscles. It is to be remembered that if these 
paralysed muscles show the reaction of degeneration, and 
if the galvanic current is used to treat the paralysed limb, 
the healthy antagonists will give a quick twitch, while the 
paralysed muscles will give a sluggish contraction which 
will long outlast the quick twitch, thereby causing a 
passive stretching of the healthy muscles ! 

In cases of infantile paralysis of the upper limb the 
same method of treatment as described for Erb's palsy 
may be used. 

Periodic examinations are to be made of the condition 
of the muscles by electrical testing. The electrical 
reactions will afford a good guide as to the progress of the 
case. In the most severe cases, in which, at the beginning 
no reactions of any kind could be obtained, the first sign 
of improvement may be a very weak, sluggish contrac- 
tion. It often happens that the return of voluntary 
power precedes any marked change in the response to 
electrical stimuli. 

It is useless to commence treatment of infantile 
paralysis unless prepared to persevere with it. It should 
be given at least twice weekly, or, better, four times 
or six times, when possible. Bergonie treats his cases 
twice daily, for half-an-hour to an hour. There is no 
fatigue produced and the best results are obtained. 

The treatment of infantile palsy should be extended 
over a period of at least six months, and left off only 
when it is evident that no improvement has taken place 
for the same period of time. 



CHAPTER X 

THE USE OF THE ELECTRICAL CURRENT FOR TESTING THE 
REACTIONS OF MUSCLE AND NERVE 

The physiological response of muscle and nerve to 
electrical stimulation may be profoundly modified in 
cases of disease of these tissues. The determination of 
the nature of the response is known as the " testing of the 
reactions," and it affords information that cannot be 
obtained in other ways, the diagnosis in some cases 
depending upon it. The testing of the reactions of 
muscle and nerve forms, therefore, an important part of 
the investigation of cases of paralysis. The reactions 
sought are the contractions that follow stimulation, first 
by the faradic current (known also as the interrupted 
current), second, by the galvanic current (known also as 
the continuous or constant current), both currents being 
appUed in succession to the muscle itself and to the nerve 
trunk that contains its motor fibres. 

The Reactions of Normal Muscle and Nerve. — When a 
muscle or its motor nerve is stimulated by the faradic 
current it will remain in continuous contraction or 
" tetanus " so long as the current flows. The contraction 
is continuous, because this current provides a number of 
stimuli repeated in rapid succession. The muscle being 
able to contract in response to each stimulus has not 
time to relax in the very short interval between two 
successive stimuli. 

When the muscle or its motor nerve is stimulated by 
the galvanic current, the muscle makes a single twitch at 

138 



APPARATUS FOR TESTING 139 

the moment when the current commences to flow. No 
contraction is seen while the current is actually flowing. 
A second twitch is seen at the moment the current ceases 
to flow (if the current is sufliciently strong). These 
responses — a continued contraction when the muscle or 
its motor nerve is stimulated by the faradic current, and 
a single twitch when they are stimulated by the galvanic 
current — are the responses of normal muscles and nerves 
and are spoken of as " reactions of normal type " or 
" normal reactions." They are altered in disease. 

In order to test the reactions we require an induction 
coil, a source of constant current, two electrodes and the 
necessary conducting wires. A convenient arrangement 
is a switch-board fixed to the wall or a movable table, to 
which are attached a rheostat, from which a constant 
current of suitable strength may be shunted from the 
main, and an induction coil which may be worked by the 
current from the main. By means of a switch either 
the faradic or the constant current may be diverted to 
the patient by way of two terminals fixed to the board. 
A milliampere -meter is provided, so as to indicate the 
strength of the constant current that is being used. A 
commutator is provided, so that the direction of the latter 
current may be reversed, if desired. A switch-board of 
the type described is shown in Fig. 21. 

If there is no main supply, or if the apparatus is to be 
portable, the combined battery shown in Fig. 42 may 
be used. Inside the case are an induction coil and a 
battery of dry cells. It is important that a coil of suit- 
able design should be used if accurate results are to be 
obtained and the testing is not to be painful. The 
subject of induction coil current is considered on page 
31, where the importance of using a proper coil is further 
emphasised. 

Two electrodes are required. One, the " indifferent " 
electrode, is of the type described and figured on page 78 ; 



140 ESSENTIALS OF MEDICAL ELECTRICITY 

it should measure six by three inches. The other, the 
" active " or " testing " electrode, is a metal disc three- 
quarters of an inch in diameter, covered with chamois 
leather, mounted on a handle, to which is fixed a 
closing-key (Fig. 43) by means of which the current 
may be sent through the patient when wished. 



Fig. 42 

The electrodes are moistened with warm salt solution 
(about 5% strength). The indifferent electrode is 
placed on some part of the body away from the muscles 
that are to be t ssted. When the upper limbs and shoulder 
girdle are to be tested, it may be placed over the sternum. 
In the case of the lower limbs it may be kept in the same 
situation or placed behind the hips. When the intrinsic 
muscles of the hand or foot are to be tested the in- 



STRENGTH OF CURRENT FOR TESTING 141 

different electrode is better placed on the palm or sole. 
When testing the face or neck muscles it may be placed 
under the palm. 

The testing electrode is placed over the muscle or nerve 
of which the reactions are required. The skin in contact 
with either electrode should be well moistened with the 
salt solution before beginning the test. 

In carr5dng out the test the faradic should always be 
used first. 

The operator should first grasp the limb to be tested 
and pass the current through his own hand, moistened 
with salt solution, as well as through the patient's 
limb. This not only gives the operator an idea of the 




Fig. 43. — Testing Electrode. The chamois-leather-covered metal 
disc screws on the end. It is not shown in the figure. 

strength of the current, but has a reassuring effect on 
the patient. Strong currents are seldom necessary in 
electrical testing. All that is required is enough to pro- 
duce a distinct contraction. The current should be just 
strong enough to produce a distinct contraction of the 
operator's dorsal interossei when grasping the patient's 
limb. This strength will be suitable for most of the limb 
muscles, but will probably have to be increased when 
testing the intrinsics of the hand and foot, with the in- 
different electrode on the palm or sole. The increase is 
necessary on account of the high resistance of the thick 
skin of the sole and palm. Muscles that lie close to the 
surface, like the facial muscles, require weaker currents ; 
those that lie farther away require stronger currents. If 
there is a thick layer of subcutaneous fat, a stronger 
current will be required. 

The various muscles that are to be tested are 



142 ESSENTIALS OF MEDICAL ELECTRICITY 

stimulated in turn with a current that is just strong 
enough to produce a distinct contraction. 

It is assumed that the operator has a knowledge of the 
anatomy of the muscular and nervous systems, including 
the action and nerve supply of the individual muscles. 
Such knowledge is absolutely essential if the examina- 
tion is to have any value. 

It is found that when stimulating any normal muscle 
there is a point where the contraction is greater, or, in 
other words, when the minimal contraction is obtained 
with a smaller current, than when the electrode is even 
but slightly moved from this point. This is called the 
" motor point " of the muscle. Each muscle has its 
motor point, and it is found to correspond to the spot 
where its motor nerve enters the substance of the muscle. 
A thorough knowledge of motor points enables one to 
carry out a test with the smallest possible amount of 
current and consequently the least discomfort to the 
patient. Speaking generally, the motor point is situated 
about the middle of the body of a muscle. Thus the 
beginner, by calling up a mental picture of the muscle 
which he wishes to stimulate and placing the active 
electrode over the middle of its body, will be either on the 
point or so near that very little exploring will discover it. 
This does not apply to all the muscles, but it does apply 
to a great many, and a knowledge of this fact is a great 
help and encouragement to the beginner. It is impor- 
tant to point out that it is not necessary, even if it were 
always possible, to throw the whole of the muscle into 
strong visible contraction. Some muscles do contract 
strongly and visibly with moderate currents ; of this, the 
biceps in the arm is a good example. The evidence of the 
contraction of others is obtained by placing the finger 
lightly over the tendon at the moment of closing the 
current. In this way the slightest contraction becomes 
manifest. The muscles of which the tendons are 



TESTING WITH GALVANIC CURRENT 143 

gathered about the wrist and ankle are examples. 
Others, again, are only manifest when the characteristic 
action of the muscle takes place, such as the supinator 
brevis. 

Muscles which are too feeble to produce their character- 
istic action can only be detected by some slight move- 
ment on the surface near the electrode. The plates 
following page 160 show the position of the motor 
points — ^they should be referred to continually, until the 
operator is perfectly famiUar with them. 

After testing the muscles with the faradic current, the 
galvanic (constant) current is used. The testing elec- 
trode is made the kathode by connecting it to the negative 
pole of the source of current. A preliminary trial of the 
strength of the current should first be made in the way 
described above, and a current should be used that is 
just sufficient to cause a twitch when the current starts. 
It is of importance to use the smallest galvanic current, 
because this current causes a more painful sensation than 
the faradic, and if strong it may be unbearable. It is 
found when testing with galvanic currents of increasing 
strength that a twitch is first noted only at the moment 
when the circuit is closed and the current is started. It 
is only when the current has been much strengthened 
that a twitch is also noticed at the moment when the 
current is interrupted. It is noticed, further, that the 
twitch seen when the circuit is closed occurs sooner (i.e. 
with weaker current) when the testing electrode is the 
kathode than when it is the anode. These twitches are 
known as the " kathodic closure contraction " (KCC) and 
the " anodic closure contraction " (ACC). The other 
twitches occurring when the circuit is opened and the 
current interrupted are called the " anodic opening 
contraction " (AOC) and the " kathodic opening con- 
traction " (KOC). 

The relative strength of the current required to produce 



144 ESSENTIALS OF MEDICAL ELECTRICITY 

each of these twitches is seen in the table below. The 
actual values depend in each case on the thickness of the 
overl5dng tissue ; when this is thicker a stronger current 
will be required : 

KCC 2 

ACC 3 

AOC 3.5 

KOC 15 

When testing the muscles and nerve trunks with the 
galvanic current, the latter should be sufficiently strong 
to produce an evident contraction with the weakest 
current when the testing electrode is the kathode and at 
the moment when the current is started by closing the 
circuit. That is to say, the testing current should be just 
strong enough to produce a distinct KCC. The strength 
of this current should be read on the miUiampe re -meter 
when the needle has come to rest. 

When stimulation of a motor point causes contraction 
of a muscle, the contraction is not due to the stimulation 
of the muscle substance, but to the stimulation of the 
motor nerve at the point where it enters the muscle ; 
this is because motor nerve is more excitable than muscle. 
When the nerve has lost its excitabihty the muscle will 
then be stimulated directly, not iadirectly through its 
nerve. It will then be found that there is no " motor 
point," and that contraction can be produced by stimulat- 
ing any part of the muscle, especially its tendinous end, 
because there the muscle is nearest to the surface. 

It wiU well repay the student to practise testing his own 
muscles, so as to gain famiharity with the position of the 
motor points, and to recognise the contraction of in- 
dividual muscles and note the behaviour of the muscles 
when the different nerve trunks are stimulated. When 
using the galvanic current the readings of the milUampere- 
meter should be always noted, so as to obtain knowledge 



POSITION OF MOTOR POINTS 145 

of the strength of the stimulus that is being used. There 
is no instrument that can be used for measuring the 
strength of the faradic current when testing, and the 
most that can be done is to make a prehminary trial in 
the way described, the operator testing the interossei 
of his own hand, duly moistened, placed in contact with 
the patient's hmb. 

The discovery of the motor points when testing is not 
the difficult task that it appears to be to the beginner 
after inspecting the plates after page 160. As already 
mentioned, he will soon remember where each one is to 
be found after some practice on his own muscles. It is a 
good plan also to study the pictures of the dissections of 
the muscles in a work on anatomy, so as to get a better 
idea of the position of the various parts. 

The position of the motor points is shown in Plates 
I. to VI. These points have not always exactly the 
same position in different subjects, but the situation as 
shown in the plates represents the average of a large 
number of cases. The position where the nerve trunks 
are most accessible for electrical stimulation are shown 
in these plates. 

How Electrical Testing is carried out. — The patient 
should recline on a couch on his back with head and 
shoulders raised. In this position the face, neck, 
arms, chest, abdomen and lower limbs may be tested. 
The back of the thigh and leg may be brought into view 
by flexion at the hip and raising them off the couch. For 
the back and shoulder muscles the patient should sit on 
the couch. For the gluteal muscles the patient must He 
face downwards. 

The indifferent electrode may be placed on the chest 
when the neck, shoulders, upper limbs and back have to be 
tested, or behind the hips when the front of the trunk 
and lower extremities are to be tested. When the 



146 ESSENTIALS OF MEDICAL ELECTRICITY 

intrinsic muscles of the hands or feet are to be tested, it 
should be placed on the palms or soles. Frequently, the 
facial muscles only are to be tested : in this case the palm 
may be placed on the indifferent electrode. The skin in 
contact with this electrode should be well moistened with 
salt solution and the electrode itself, similarly soaked, 
should make good and even contact. 

The part to be tested should now be moistened with 
salt solution. One hand of the operator, similarly 
moistened, should grasp the part ; the induction coil is 
started and the active electrode, also moistened with the 
same solution, placed on the back of the operator's hand 
over the first dorsal interosseous muscle. The key on 
the electrode should then be closed, so as to allow the 
current to flow and ascertain its strength. When strong 
enough to cause distinct contraction of the muscle 
mentioned, the electrode should be placed over the motor 
point of each muscle in turn that is to be tested, and 
the key depressed for a moment, so as to ascertain the 
response of each muscle. The position of the electrode 
should be adjusted so as to lie directly over the motor 
point, and when this has been done the most vigorous 
contraction will be produced. 

When testing with the faradic current the following 
inquiries should be made : 

(i) Is there any response of the muscles at all ? Be 
sure that the electrode is on the motor point 
and that it is making good contact, also the 
indifferent electrode. 
(2) Is the response of the muscles much enfeebled ? 
In some cases the weakening will be quite 
apparent. In others it will be very difficult to 
decide whether the response is weaker than 
normal. There is no ready method of measuring 
the response, and, as already said, there is no 
way of measuring the strength of the faradic 



TESTING WITH THE GALVANIC CURRENT 147 

current. Some information may be obtained 
by comparing the response given by the same 
muscle of the opposite side (if healthy) under the 
same conditions and with the same precautions ; 
small differences are very difficult to detect, 
but they are not of much importance for 
diagnosis. 
(3) Is the response of the muscles much increased? 
Here again small iacreases are not of im- 
portance, and are difficult to diagnose with 
certainty. 
After testing each muscle with the faradic current, 
repeat the test with the galvanic current. It is in- 
sufficient to bring the test to a close without using the 
galvanic current, unless the operator can say for certain 
that the contractions produced by the faradic current 
are not weakened, and it is sometimes difficult to be sure 
on this point. And it is incorrect to say that the reaction 
of a muscle is normal because it contracts in response 
to the faradic current. Muscles of which the reactions 
axe certainly abnormal are frequently seen in which there 
is some response to the faradic current, or a response 
when this current is made stronger. 

When using the galvanic current, make the testing 
electrode the kathode, and make a preliminary trial of 
the strength of the current, and when testing the patient's 
muscles use a current that is just strong enough to pro- 
duce a distinct twitch of the muscle at the moment when 
the key is depressed and the circuit completed. Make 
the following inquiries : — 

(i) Is the twitch smaller or larger than normal, or 
is it absent altogether? The same difficulties 
present themselves when trying to settle the 
question of the size of the twitch whether larger 
or smaller than normal. Small differences are 
unimportant. The reading of the milliampere- 



148 ESSENTIALS OF MEDICAL ELECTRICITY 

meter gives some measure of the strength of the 
stimulus, but the actual number of the milU- 
amperes required to produce a twitch will vary 
from patient to patient even if the muscles are 
normal. The number of milhamperes will also 
vary, slightly, from muscle to muscle ; the 
farther the motor point beneath the skin, the 
stronger will be the stimulus necessary. But 
in making comparisons with the muscles of the 
opposite side (if they are normal) the reading of 
the milliampere-meter will indicate whether an 
equally strong stimulus is being used on both 
sides. 
(2) Is the twitch quick like that customary for 
normal muscles, or is it slow and sluggish ? 
Under certain circumstances (to be mentioned 
hereafter) the response of the muscle is quite 
different from that which is seen in health. 
Instead of the brisk twitch, there is slow, lazy 
shortening and relaxation of the muscle that 
sometimes looks like a peristaltic wave. When 
testing, therefore, with the galvanic current, it 
must be noted whether the response is a quick 
twitch or a sluggish contraction. 

It will be noted that when the muscle makes 
this slow response, the current will often evoke a 
bigger contraction when the electrode is off the 
motor point, and that the biggest responses are 
obtained when the electrode is at the peripheral 
end of the muscle . Sometimes it will be found — 
and this is very important — ^that the muscle will 
give a quick twitch when the electrode is placed 
on its motor point, but a sluggish contraction 
when placed on the peripheral ends. It is 
therefore always advisable when in doubt 
whether the response to the galvanic current is 



TESTING NERVE TRUNKS 149 

quick or slow, to stimulate the fleshy extremities 
of the muscle and inquire — 
(3) Is the contraction produced by stimulating the 
peripheral end of the muscle slower than that 
produced by stimulating the motor point ? 

Testing the Nerve Trunks. — ^After testing the muscles, 
proceed to test the main nerve trunks in which lie the 
motor supply. The testing electrode should be placed 
over the nerve trunk ; the indifferent electrode must be 
placed so that when the current flows none of the muscles 
that are suppHed by the nerve will be traversed by it, 
and so possibly be stimulated to contract. 

The nerve is tested first with the faradic current, and 
it should be noted whether the muscles respond or not. 
If any of them do not respond, the nerve is tested with 
the galvanic current, using the kathode as the testing 
electrode, and again it should be noted whether the 
muscles contract or not. If the paralysis is due to injury 
the nerve should be tested wherever possible above and 
below the site of the injury and in the region of the 
injury itself. 

The points for stimulating the principal nerve trunks 
are shown in Plates I. to VI. 

Types of Electrical Reaction of Muscle and Nerve. — 

(a) Normal Type. — When a muscle and its motor nerve 
are healthy it contracts when stimulated by the faradic 
current and remains contracted so long as the current 
flows. The same response is noted when its motor nerve 
trunk is stimulated. With the galvanic current a single 
quick twitch occurs at the moment the circuit is com- 
pleted or closed. This twitch is known as the " closure 
contraction," and when the testing electrode is the 
kathode, it is called the " kathodic closure contraction," 
or, for short, KCC. A similar quick twitch occurs when 



150 ESSENTIALS OF MEDICAL ELECTRICITY 

the galvanic current stimulus is applied to the nerve. 
These reactions are known as normal reactions. 

When the test is being made and the muscle contracts 
strongly when the faradic current is used, it may be 
almost certainly said that its reactions are normal. But 
it is not always easy to be sure whether the contraction 
caused by the faradic current is of normal strength, 
especially as there is no method of measuring the strength 
of this current. It is always advisable when in doubt 
to use also the galvanic current, testing the muscle at its 
motor point and peripheral end where it joins its tendon. 
If the muscle is normal, it will contract quickly when 
stimulated at its motor point, and not at all when stimu- 
lated at its peripheral end — that is, if the current is not 
strong. If the current is strong, there may be a con- 
traction when the peripheral end is stimulated, but it is 
always feebler than that seen when the motor point 
is stimulated. 

(b) Normal Type, but weakened {Weak Normal). — In 
some cases it will be noted that the contraction produced 
by the faradic current is obviously weakened. When the 
galvanic current is used and the twitch is feebler than 
normal, but not slow, the reactions of the muscles are of 
the normal type, but weakened. The muscle is said to 
show " weak normal " reactions. It is necessary to be 
sure that the response to the galvanic current is quick. 
This is not always easy. The muscle should be tested 
at its peripheral end as well as at its motor point, as 
mentioned under {a). 

Small diminutions of excitability are not easy to be quite 
sure of, owing to the difficulty in obtaining at all times 
exactly similar conditions in aU parts of the circuit. The 
degree of moisture and thickness of the skin, the pressure 
of the electrode, and its position are all possible disturbing 
factors. Where the disease is unilateral the difference 
in the behaviour of the two sides is the best guide, but 



REACTION OF DEGENERATION 151 

even here a difficulty arises in the fact that the skin of a 
paralysed limb sometimes has a much higher resistance. 
Fortunately the lesser degrees of quantitative change 
have little or no diagnostic value. 

(c) In some cases it may be noticed that there is absence 
of excitability to both faradic and galvanic currents. 

(a), (b) and (c) are examples of quantitative changes in 
the reactions^-differences in degree, not in kind. 

{d) In many cases it is noticed that the muscle does 
not contract at aU when stimulated by the faradic 
current, and gives a sluggish contraction in response to 
stimulation by the galvanic current. Such a muscle is 
said to show the " reaction of degeneration." The 
symbol RD is generally used as an abbreviation for 
reaction of degeneration. When the nerve is tested, it 
will be found in many cases to be inexcitable by either 
current. The muscle is then said to show the complete 
reaction of degeneration (CRD). Sometimes, however, 
the nerve will respond to both currents or only to the 
galvanic. 

It is sometimes found that muscles showing RD will, 
when stimulated by the galvanic current, at the moment 
when the circuit is closed give a larger contraction when 
the testing electrode is the anode than when it is the 
kathode, whereas the reverse is true for normal muscles. 
It was formerly thought that this alteration in which 
the ACC is greater than the KCC occurred in all cases of 
RD. It is, however, by no means a constant feature, 
and it sometimes depends on the chance position of the 
testing electrode. This " polar reversal," as it is some- 
times called, is no longer included as essential for the 
diagnosis of RD. 

{e) In some cases it is found that the muscle will 
respond, though feebly, to the faradic current, but gives 
a sluggish response to the galvanic current. Such a 
muscle is said to show the " partial reaction of degenera- 



152 ESSENTIALS OF MEDICAL ELECTRICITY 

tion " (PRD). The distinction between this reaction 
and the weak normal reaction depends, therefore, on the 
response to the galvanic current, whether slow or quick. 
It is often difficult to decide this point. As already 
mentioned under (a) and (h), the peripheral ends of 
the muscle should be tested, and if the contraction is 
larger or slower than when stimulated at its motor 
points, the reaction may be regarded as a reaction of 
degeneration. 

The anodic closure contraction should also be obtained 
and compared with the kathodic closure contraction, 
and if it is larger it provides additional evidence in favour 
of the reaction of degeneration. But if the anodic 
closure contraction is smaller than the kathodic, it does 
not exclude the possibility of the reaction of degeneration. 

When a muscle shows a stronger and slower contrac- 
tion when it is stimulated at its tendinous end than when 
it is stimulated at its motor point, it is said to show the 
" longitudinal reaction." It is really part of the reaction 
of degeneration. 

(/) In Thomsen's disease (Myotonia) it is found 
that when the muscles are tested with the faradic 
current the contraction persists for some seconds (some- 
times as long as thirty seconds) after the current has 
been stopped. The same thing is noticed when the 
galvanic current is used ; instead of a momentary twitch 
there is a prolonged contraction which lasts while the 
current is flowing, and persists from five to thirty seconds 
after it has ceased. This reaction is known as the 
myotonic reaction. It is characteristic of Thomsen's 
disease. 

When a muscle shows RD the contraction produced by 
the galvanic current is sometimes seen to persist while the 
current flows. Such a contraction is caUed " galvano- 
tonus," or " duration tetanus," but it does not persist 
when the current ceases to flow. Duration tetanus is 



MEANING OF DIFFERENT REACTIONS 153 

sometimes seen in healthy muscles when the galvanic 
current is strong. 

(g) In myasthenia gravis the muscles are very quickly 
fatigued and their responses rapidly get weaker during 
the process of testing, with either faradic or galvanic 
current. The excitabihty may even be lost, but it 
returns after rest. The reaction is known as the 
" myasthenic reaction." 

(h) Rich's Reaction. — In this reaction a twitch is 
obtained (using the kathode as the testing electrode) at 
the moment when the circuit is opened and the current 
ceases to flow, with a current that is just strong enough 
to produce a KCC in a normal muscle. In normal 
muscles it requires a much stronger current to produce 
a KOC than a KCC. 

The different reactions may be tabulated thus : 

Reactions of Normal Type Reactions of Abnormal Type 

Normal. I. Reaction of Degeneration. 

Weak Normal Reaction. (i) Partial. 

Strong Normal Reaction. (2) Complete : 

Rich's Reaction. (a) With loss of excita- 

bility of nerve to 
both currents. 
(5) With loss of excita- 
bility of nerve to 
faradic current, not 
to galvanic. 
{c) With no loss of ex- 
citability of nerve. 
II. Myotonic Reaction. 
III. Myasthenic Reaction. 

Meaning of the Various Types of Electrical Reaction.— 

When a muscle shows the reaction of degeneration it 
indicates that there is a lesion somewhere in its motor 
neuron and localised to the lower neuron. There maybe 
either injury or disease, and it may affect any part of the 
lower motor neuron, either the motor nerve cells of the 
anterior horn of the spinal cord (or in the case of a cranial 
nerve the cells of its motor nucleus) or the motor nerve 



154 ESSENTIALS OF MEDICAL ELECTRICITY 

fibres or their end plates. If the lesion affects the upper 
motor neuron {i.e. the nerve track between the cerebral 
cortex and the anterior horn cells) the reaction of 
degeneration is not seen. 

It further indicates that the lesion is of some degree of 
severity. Slighter degrees of injury or disease wiU pro- 
duce simply quantitative alterations of the reaction — 
that is to say, the reaction will be of the normal type, 
but the contractions to both currents wiU be weaker. 

When the reaction of degeneration is partial {i.e. when 
there is some survival of excitability to the faradic 
current) it may be taken to indicate that the lesion is less 
severe than when the reaction is complete. Direct stimu- 
lation of the nerve gives information on the condition of 
the latter. If the nerve retains its excitability to both 
currents and its conductivity (as shown by the contrac- 
tion of the muscles when the nerve is stimulated), it is 
an indication that it is less severely damaged than when 
its excitability and conductivity are lost. In some 
cases the nerve loses its excitability to the faradic current, 
while retaining it to the galvanic current. This, prob- 
ably, indicates a condition intermediate between those 
in which there is complete loss of excitability to both 
currents and the retention of excitability to both currents. 

Weak normal reactions are found in milder cases of 
injury or disease of the lower motor neuron — cases which 
would, if more severe, show RD. 

Increased normal reactions occur in cases of paralysis 
in which there is a lesion in the upper motor neuron. 
Vigorous reactions of the normal type are seen in tetany. 

The myotonic and myasthenic reactions are character- 
istic of the diseases known as myotonia (Thomsen's 
disease) and myasthenia gravis. 

Rich's reaction is supposed to occur in muscles para- 
lysed as the result of pressure on the nerve trunk. 

The motor nerve ceUs and their fibres do not solely 



FIRST APPEARANCE OF RD 155 

serve the purpose of conveying impulses causing con- 
traction. The anterior horn cells exercise influence 
over the condition of the contractile substance of the 
muscle. When the motor nerve is permanently severed 
the muscles will gradually degenerate and ultimately be 
replaced by fibrous tissue, although it retains its blood 
supply and is made to contract artificially by electrical 
stimuH. 

The behaviour of a muscle under electrical stimulation 
when the nerve has been sufiiciently injured or diseased 
to show RD has been explained in the following way by 
Mile loteyko. The muscle is supposed to contain con- 
tractile substance of two kinds : (i) a striated portion 
which contracts briskly and will respond to very brief as 
well as to slow stimuli ; (2) the undifferentiated sarco- 
plasm, which contract sluggishly and require long 
duration impulses to cause it to contract. When the 
nerve has been injured or diseased the striated portion 
degenerates or becomes functionless much more quickly 
than the sarcoplasm. Hence very brief stimuli, such as 
supplied by the induction coil, will not cause contraction, 
because the striated portion has passed out of use and the 
sarcoplasm is unable to respond to very brief stimuU. 
The sarcoplasm can, however, contract when stimulated 
by the slower impulse of the galvanic current and con- 
tract slowly, as is its custom, when the striated portion is 
not in action. 

Course of the Reaction of Degeneration: its First 
Appearance. — ^The reaction of degeneration does not 
appear at the onset of disease or injury of the nerves, 
even when these have been completely divided. After 
complete division of its nerve the muscle ceases to respond 
to the faradic current in from four to seven days, while, 
according to Sherren, the sluggish response to stimula- 
tion with the galvanic current begins about the tenth 



156 ESSENTIALS OF MEDICAL ELECTRICITY 

day. The actual time at which RD is fully developed 
probably varies in different cases, according to the 
exciting cause. 

If the muscle has been completely and permanently 
cut off from the anterior horn ceUs, the reaction of de- 
generation persists, but becomes slowly and progres- 
sively feebler, and, after one year, it may be impossible 
to elicit any response to electrical stimulation. 

In less severe injury, when the muscle has not been 
permanently cut off from the influence of the anterior 
horn cells, RD may persist for a longer time and, if 
recovery takes place, there may be no period during 
which there is no response to electrical stimuli. 

RD may persist for several years. Lewis Jones be- 
lieved that this persistence of RD indicated that there 
were still some representations of the muscle in the 
anterior horn of the spinal cord. 

Prognosis of RD. — ^It must not be thought that a 
muscle with RD is irreparably damaged and that normal 
reactions cannot return. The recovery of normal re- 
actions is a frequent occurrence, and it is often found that 
voluntary power returns and becomes fairly good before 
the RD has disappeared. The author has kept some 
cases showing RD under observation for considerable 
periods and has noted return of voluntary power nearly 
equal to that of the sound muscles on the opposite side, 
and recovery of the size of the affected limb with per- 
sistence of RD. In these cases the motor nerve had not 
lost its excitability. 

In cases of injury to nerves the operator is asked to 
report on the electrical reactions of the muscles and give 
an opinion whether the nerve is divided or not. The 
question is often very difficult to answer. If the muscle 
shows RD that is partial it indicates that there is still 
physiological and anatomical connection between the 



DIFFICULTIES IN TESTING 157 

muscle and the spinal cord, and the outlook is favourable. 
If the RD is complete, but the nerve retains its excita- 
bility to one or the other current, the outlook is also 
favourable. If the RD is complete and the nerve in- 
excitable, then the prognosis is very uncertain and there 
is no electrical test that will show whether the injury 
that has separated the muscle from the influence of the 
anterior horn cells has either divided the nerve trunk 
completely (or severed the fibres within the sheath), or 
has bruised it sufficiently to separate the muscle from 
the influence of the anterior horn ceUs for a short time or 
a long time. If the excitability of the nerve to electrical 
stimulation has disappeared and that of the muscle has 
disappeared or is disappearing, the damage to the nerve 
has been sufficiently severe to caU for surgical exploration. 

Practical Difficulties in Testing.— When the operator 
has become familiar with the position of the motor points 
there will be little or no difficulty in testing when the 
reactions are normal or when the complete reaction of 
degeneration is present. The chief difficulty lies in the 
decision whether a muscle shows a weak normal reaction 
or a partial RD. The decision depends on whether the 
response to the galvanic current is quick or slow. In 
some cases the response is so slow that there is no difficulty 
in diagnosing the reaction as partial RD. In other cases 
it is very difficult to be sure whether the response is quick 
or slow. In these cases the tendinous end of the muscle 
should be tested with the galvanic current. If this is 
done and the response is weaker than that seen when the 
motor point is tested the muscle has probably a weak 
normal reaction. If, on the other hand, the response 
seen when the tendinous end is stimulated is certainly 
as large as, or larger than, that noted when the motor 
point is stimulated, and especially if it is slower, the 
muscle has most probably shown a partial RD. 



158 ESSENTIALS OF MEDICAL ELECTRICITY 

It is often difficult to be sure whether a reaction is 
normal or weak normal. It is almost impossible to be 
sure of small differences in the amount of the response to 
electrical stimulation, but small differences are not of 
importance for the purpose of diagnosis. The method 
of testing by condenser discharges will be of help in this 
matter (see below). ' 

Defects of the Method of Testing by Faradie and 
Galvanic Currents. — The method of testing by means of 
the galvanic and faradie currents has various defects. 
In the first place, the strength of the faradie current is 
not, in practice, measurable, while the duration of the 
separate impulses varies in different coils and is always 
longer than the shortest to which healthy muscle can 
respond, and often it is very much longer. A muscle will 
have passed out of the normal if it requires an impulse 
as long as that furnished by many induction coils 
before it will contract. It does not necessarily follow, 
therefore, that a muscle must be normal because it 
responds to the faradie current. On the other hand, 
although the strength of the galvanic current can be 
measured by the milliampere-meter, the time during 
which it is allowed to flow is not measured and is always 
too long. 

Testing by Means of Condenser Discharges. — ^By this 
method the strength and duration of the impulses is 
measured. The apparatus consists of a box of condensers 
which vary in capacity between o-oi microfarad and 
2-00 microfarads. There are ten intermediate sizes. 
By means of a metronome any one of these condensers 
can be alternately charged to a known voltage from the 
main and then discharged through the patient. The 
duration of the discharge of a condenser depends, (i), on 
its capacity : the larger the capacity the longer the dura- 
tion ; (2), on the resistance of the circuit along which 



TESTING BY CONDENSER DISCHARGES 159 

the condenser discharges. The chief resistance in the 
circuit is the body. For impulses of very short duration 
the resistance of the body is constant and may be taken 
as 1000 ohms in the condition under which the test is 
performed. 

The smallest condenser in the box would then give an 
impulse lasting only .,^ ioo ^^ of ^ second, the largest 
condenser -^ of a second. The voltage to which they 
are charged can be varied ; usually it is 100. 

To carry out a test the muscles are tested successively 
with the condensers, beginning with that of the smallest 
capacity and proceeding till one is found to which the 
muscles will just respond. The capacity of this con- 
denser or the duration of its discharge through the body 
gives the measure of the condition of the muscle. There 
is no need to decide whether the contraction is quick or 
slow. 

It may be taken that muscles with reactions of the 
normal type will require condensers of capacities 
measured in hundredths of a microfarad (o-oi to 0-09), 
according to the degree of departure from the normal ; 
muscles with a partial RD require condensers measured 
in tenths of a microfarad (o-io to 0-90) ; muscles with 
complete RD require condensers of one or more micro- 
farads. 

Instead, therefore, of three types of reaction — ^normal, 
partial RD and complete RD — ^we have twelve degrees 
of departure from normal, each being represented 
niunerically. 

After the new apparatus had been used for testing it 
was soon found that many muscles showing RD could not 
respond even to the largest condenser (2-00 microfarads). 
This condenser does not provide an impulse long enough 
for most cases of RD . Bigger condensers cannot be used, 
because when charged to 100 volts their discharge gives 
too great a shock. The difficulty may be surmounted 



i6o ESSENTIALS OF MEDICAL ELECTRICITY 

by enclosing an additional resistance in series with 
the patient. This has the effect of lengthening the 
duration of the discharge. Thus by using a resistance of 
5000 ohms the discharge of the condensers through the 
body can be increased sixfold. It is thus possible to 
increase the duration of discharge of the 2*00 microfarads 
condenser to ^V^h of a second. Another way of over- 
coming the difficulty is to use condensers larger than 
3-00 microfarads, but charge them to a lower voltage, 
say 50. Muscles with RD sometimes will respond to 
discharges at lower voltage than will normal muscles. 

It was further found that muscles showing partial RD 
varied greatly with regard to the capacity of the con- 
denser required to make them contract. Some required 
large condensers (tenths of a microfarad), but many others 
would respond to much smaller condensers. There are 
thus many varieties of partial RD. 

The testing of the reactions of muscle and nerve by 
condenser discharges has the following advantages. The 
method is more accurate because we are using measured 
stimuli, their duration varying between the shortest to 
which normal muscle and nerve will respond and the 
longest required for the same tissues when in a condition 
of degeneration. In the older method we use only two 
stimuli, the faradic and galvanic currents, the duration 
of both of which are unmeasured, the former being not 
short enough, the latter too long. The new method 
yields more information. The degree of deviation from 
the normal can be expressed accurately, in terms of the 
length of the discharge that is just able to provoke a 
response from the muscle or nerve. A test made by the 
condenser method causes much less pain than that pro- 
duced by the galvanic current, and it takes less time. 



PLATE I 



M. frontalis 

Upper branch qf/aeUU 

U. corrug. supeicil. 

H. orbic. p*lpet>r. 



M. zygimiatici 

K. orbicul. arte | 

Uiddit branch (ff facial 

H. leTatoT ment; 
M. qoadr. menti 
X. triaog. menu 



[Mter brunch offaeiaX 

M. pUtysma mjold. 

Hyoid muicles | 

U. omohyotdeos 



Ant. thoraeU «i 
(M. pectoial.) 




Eegion of Snl frontal 
con-T. and island 
of Bell (centre for 



HL temporalis 



forfain, (trunk) 
Pott, aurkvlar n. 
Middle branch of facial 
Lower branch (^facial 
K. spleniM 
U. gtemocleido- 

inaktoideus 
!^^tmiU aeeeuory n. 
SC l«Tato» angnli scapoL 



Long thoracic n. ( M. 
eerrat.aat.B«j.) 



Phrenic n. Si^raeleaiicular point. Brachial plexui. 
(Erb 8 point. H. deltoid., 
biceps, brachialia intern. 
And sapJi. long.) 



Med. Elec 



PLATE II 



]|.latenMa.domLI. 
•tU. 



trioep3(c>4>at 




PLATE III 



M. triceps (long head) 

U. triceps (inner bead) 
Dinar h, | 



If. flexor car})I ainaria 



M. flex. i1if;ltor. commun. 
prufuud. 



:. flex, (ligitor. snblim. 
(digiti II. ct lU.) 



, flet. digit, siubl. (digit 
indicia et miniuii) 



M. polnuuris brev. 

M. abductor digiti niin. 

M. Oexor digit, min. 

U. opponens digit, min. 



Mm. lOMbrlcales ^ 



li. bleeps bxmcbb 




M. abdactor pollia I 
M. opponeni poUiois 

VL flex. poll. breT. 

M. adductor pollic. brer. 



Med. Elec* 



PLATE IV 



CrunUn. 



it. iMlductor magnns 
U. adduct. longos 




M. vastus internus 



M. tcusor fosciiB lata 



li, quadriceps fctnorU 
(common point) 



M. rectus femorls 



M. castas eztcrniu 



PLATE V 



U. tibiaL antio. 



U. cxtecs. digit, 
long. 



M. peronens breria 



M. extensor hollucia 
long. 



Xm. iatcronei don&ltt 




M. gastrocnom. extent. 
21. peronctw lougtu 



U.aoIew 



M. flexor balluds louff. 



M. exteoa. digit, comtn. 
brevi» 



U. abductor <IIgiU nin. 



PLATE VI 



M. glutcui m&daai 




PLATE VII 



Great occipkal — -A— 



Small occipital 
(cervical plexus) 



Great auricular 

(cervical plexus)'" — -> 




5th, supra-orbital branch 
5th. auriculo temporal branch 



5th. infra-orbital branch 



5th. inferior dental branch 

Superficial cervical 
(cervical plexus) 



PLATE VIII. 



Supra-clavicular nerves 



Circumflex 



Musculo-spiral external 
cutaneous branch 



M uscuJo-cutaneouB 



Median 




Intercostal humeral 



Lesser int. cutaneous 



Internal cutaneous 



Ulnar 



PLATE IX 



Intercostal humeral 



Lesser inter, cutaneous 



Internal cutaneous 



Ulnar 




Supra-scapuiar 



Circumflex 



Musculo-spiral int. cut 
blanch 



Musculo-cutaneous 



Musculo-spiral external 
cutaneous branch 



Radial 



PLATE X 



Genito-crural 



External cutaneous— -\— 



Anterior crural middle 
cutaneous branch 



External popliteal 



External saphenous 




Ilio-inguinal 



Anterior crural 
(int. cutaneous branch) 



Anterior crural 
Aong saphenous branch) 



Musculo-cutaneous 
Anterior tibial 



PLATE XI 



Inferior gluteal 



f^nterior crural, internal 
cutaneous branch | i 



Post tibial 




- — External cutaneous 



Great 
Small 



Sciatic 



Ext. popliteal 



Ext. saphenoC 



CHAPTER XI 

HIGH-FREQUENCY CURRENTS 

A HIGH-FREQUENCY Current is one that periodically 
reverses the direction of its flow at an exceedingly high 
rate. A current may be made to reverse its direction any 
number of times per second, but when the frequency of 
reversal is sufficiently high the physical properties of 
the current and its action on living tissues are profoundly 
altered. The current is no longer able to produce 
chemical (electrolytic) changes in solutions of salts, nor 
is it able to evoke a response from the excitable tissues. 
The frequency of reversal may be called high when the 
current is unable to produce these chemical changes or 
to stimulate muscle and nerve to give their customary 
response. Such a frequency would be about a miUion 
times a second. 

How High-Freauency Currents are produced. — ^A con- 
tinuous current may be made to reverse its direction 
periodically by means of a simple apparatus known 
as a current reverser or commutator. No mechanical 
apparatus of this kind can produce a sufficiently high 
frequency of reversal, and the current is generated on 
quite a different principle. 

If a condenser, such as a Leyden jar, is charged and 
then discharged, the current that flows during the period 
of the discharge, though of momentary duration, will be 
a high-frequency current if certain requirements are 
fulfilled in the circuit along which the discharge takes 
place. The resistance of the circuit must not exceed a 
L i6i 



i6z ESSENTIALS OF MEDICAL ELECTRICITY 

certain value. In the second place, the circuit must be 
arranged so that self-induction (page 287) can take place 
along it. Both these requirements will be satisfied if 
the circuit is constructed of a thick copper wire bent in 
the form of a spiral. If the discharge takes place along 




Fig. 44. — D'Arsonval's Transformer 



such a circuit, the current that traverses it will flow or 
oscillate backwards and forwards from one coat of the 
condenser to the other, getting successively feebler with 
each reversal till it dies away. At this moment the con- 
denser is discharged. All this takes place in a very brief 
period of time, its duration depending on the capacity 
of the condenser, and the resistance of the circuit and the 



HIGH-FREQUENCY APPARATUS 163 

amount of self-induction that takes place in the circuit. 
If these factors are known the number of oscillations 
per second (i.e. the "height" of the frequency) can be 
calculated. 

Apparatus for the Production of High-Frequency 
Currents. — ^The arrangement of Leyden jars and wire 




■OFO 



i—5 



mmm 



Fig. 45. — Plan of High-Frequency Arrangement 

Spiral is shown in Fig. 44, and the plan is shown in 
Fig. 45 and is known as a d' Arson val transformer. It 
is named after Prof. d'Arsonval, of Paris, the pioneer 
worker in high-frequency currents in their physiological 
and medical application. It is a simple device for 
converting or transforming continuous currents or 



i64 ESSENTIALS OF MEDICAL ELECTRICITY 

alternating currents of low frequency into others of 
high frequency. In Fig. 45, C and D represent the 
condensers (Leyden jars) in section, each with its outer 
and inner coat and the intervening insulating material 
(glass). The inner coatings are connecting to the 
terminals of an induction coil. The outer coats are 
connected by the wire spiral, E. This spiral is made of 
twenty turns of thick copper wire. It is known as the 
" solenoid." Sometimes a movable handle is fitted so 
that the number of coils included between the outer 
coatings of the jars may be varied. 

Sliding rods with a ball at one end and an ebonite 
handle at the other are attached, one to each metal pillar 
that makes contact with the inner coating of each jar. 
The space between the baUs is the " spark-gap," and it 
can be varied by sliding the rods to or from each other. 

The jars may be charged from a static electrical 
machine, or from an induction coil. The usual source is 
a large induction coil of the type used for X-ray work. 
When the induction coil is used we are really deriving 
our supply from a constant current (taken from the 
mains or a battery), and the induction coil serves to 
transform this current, raising its voltage to the necessary 
degree. The alternating current from the mains may 
also be used to charge the jars after its voltage has been 
raised suitably by a static transformer. When the in- 
duction coil is set in action and the spark-gap sufficiently 
narrowed a torrent of noisy sparks darts across the gap, 
and at the same time the solenoid is traversed by high- 
frequency currents. The following events take place. 
The inner coats of the jars are charged, one positively, the 
other negatively. Charges of opposite sign are induced on 
the outer coats. The charges on the inner coats neutraUse 
each other by sparking across the gap and simultaneously 
the induced charges on the outer coats neutralise each 
other and a momentary current passes along the solenoid. 



INTERMITTENT OSCILLATIONS 165 

This current is a high-frequency current, because the 
solenoid has a low resistance and allows sufficient self- 
induction to take place. 

The sparks that appear at the gap seem to follow each 
other without intermission, and hence it would appear that 
the charging and discharging of the jars are continuous, 
giving rise to sustained high-frequency currents along the 
solenoid. This, however, is not the case. The jars are 
charged only at the moment when the " break " current 
is induced in the secondary wire of the coil. They are 
therefore charged not continuously but intermittently, 
the actual number of times per second depending on the 



Fig. 46. — Intermittent Trains of Oscillations 
a to b — Train of oscillations, lasting ^ sec. 
b to c — Intermission, lasting y^g- sec. 
c to d — Next train of oscillations 

rate at which the interrupter makes and breaks the cur- 
rent suppUed to the coil. Suppose that this rate is 100 
per second. Each tw^^ ^^ ^ second the jars are charged 
and discharged, giving rise to a high-frequency current 
in the solenoid. But the jars take a much shorter time 
than yjo^h of a second to completely discharge. It may 
be taken, for jars of the capacity used in the d'Arsonval 

transformer, as -_i-- th of a second. It follows that every 
5 0,0 00 "^ 

yi^th of a second a train of high-frequency oscillations 
lasting g^^^^ traverses the solenoid. The high-frequency 
current as suppHed by the d'Arsonval transformer is, 
therefore, intermittent, short trains of oscillations 
separated from one another by very much longer intervals 
of rest. It may be represented as shown in Fig. 46. 



i66 ESSENTIALS OF MEDICAL ELECTRICITY 



Although the actual resistance of the solenoid to a 
direct current is extremely low, its resistance to the high- 
frequency current is very great, even though the potential 
difference between the outer coats of the Leyden jars is 
very high, amounting to many thousands of volts. This 
is because the wire of the solenoid is bent in the form of a 
spiral with closely adjacent coils so that other currents are 
induced in the same circuit. It will be remembered that 
the moment a current begins to flow alongaspiral, another 
current is induced in the same circuit and flows in the 

opposite direction and 
impedes it. The in- 
duced current is only of 
momentary duration, 
so that its only effect 
on the other current 
is to impede it at its 
commencement and so 
retard its rate of growth 
to its maximum. But 
if the inducing current 
lasts only for the same 
brief period as the self- 
induced current it will 
be opposed considerably and prevented from growing to 
its full strength. The high-frequency current flows only 
for a moment in one direction before it reverses, and 
it is therefore greatly opposed by the currents it induces 
in its own circuit. If a straight wire connects the ends 
of the solenoid the high-frequency current will travel by 
preference along the former, even if it has to spark 
across a small air-gap in the circuit, and so overcome 
a high resistance. If the high-frequency current is to 
be applied to the body it is led off from the termina- 
tions of the solenoid by means of suitably insulated 
cables. 




Fig. 47. — Hot-wire Milliampere-meter 



HOT-WIRE AMPERE-METER 



167 



Measurement of High-Frequency Currents. — ^Alternat- 
ing currents, whether of high or low frequency, cannot 
be measured by the 
ampere - meter de- 
scribed later (page 
283), because their 
direction is con- 
stantly reversing. 
The hot-wire ampere- 
meter may, however, 
be used for the pur- 
pose (Fig. 47). In 
this instrument the 
current is led through 
a fine wire, of high 
resistance. The wire 
is heated in propor- 
tion to the strength 
of the current, so 
that it lengthens to 
a corresponding de- 
gree. The degree of 
lengthening is indi- 
cated by a needle 
moving over a scale 
cahbrated so that a 
certain number of 
divisions correspond 
to a known current 
passing along the 
wire. 

The current sup- 
plied by the d'Arson- 
val apparatus may ^^^- 48-High-frequency Outfit 

reach a strength of 0*5 or o-6 amperes (500 or 600 
milliamperes) when traversing the body. 




i68 ESSENTIALS OF MEDICAL ELECTRICITY 

A complete form of high-frequency apparatus is shown 
in Fig. 48. The various parts are mounted on a trolley. 
The Leyden jars are on the lower shelf ; in front of them 
is the spark-gap, enclosed in a glass cylinder to diminish 
the noise of the sparks. Above the jars is the solenoid. 
On the top of the trolley is the " resonator " (see later, 
page 170). 

How High-Freauency Currents are applied to the Body.— 

(i) The Direct Method. — The extremities of the solenoid 
are connected to electrodes placed in direct contact with 
the skin. The electrodes are made of sheets of pUable 
metal, such as copper, lead or tin cut to suitable sizes. 
They are placed in contact with the previously moistened 
skin and secured in position by a bandage or sand-bag. 
The metal should make even contact all over. Instead 
of placing the metal in direct contact with the skin, a 
pad of absorbent material, such as Unt, soaked in salt 
solution may be interposed. Its thickness should be 
that of eight layers of lint, and its area should be slightly 
larger than that of the metal plate. It is soaked in a 
solution of salt so as to enable it to conduct the current 
readily. The strength of the solution should not be 
less than 5%. The metal plates are connected to the 
extremities of the solenoid by thickly insulated cables. 
Of the electrodes, one is the cctive electrode and is placed 
on the part to be treated. The other is the indifferent 
electrode. It is of larger size than the active electrode 
and is placed on some convenient part, preferably on the 
opposite aspect of the body. A second active electrode 
may be used instead of the indifferent electrode and both 
placed on the part requiring treatment, one on one side, 
one on the other. 

(2) Indirect Method. — ^Instead of placing the indifferent 
electrode in direct contact with the body it may be placed 
a little distance away with the intervening space occupied 



AUTO-CONDENSATION COUCH 169 

by some insulating material. Such an arrangement is 
seen in the "condenser couch" or "auto-condensation 
couch" (Fig. 49). This couch contains a long metal 
plate fixed under the upholstery and insulated from 
it. It is connected to one extremity of the solenoid. 
The patient Ues on the upholstery, and the other 
end of the solenoid is attached to a metal handle, 
fixed to the couch and grasped by the patient, 
or to an electrode placed on any desired portion of 
the skin. The couch is called a " condenser couch," 




Fig. 49. — Auto-Condensation Couch 

because the patient and the metal plate form the arma- 
tures of the condenser and the intervening insulating 
material the dielectric (see page 261 for description of 
condensers). The patient and the metal plate are 
alternately charged and discharged with a frequency 
corresponding to that of the oscillation of the current. 
The current surges to and fro and into and out of the 
patient, so that the whole body is brought under the 
influence of the current, and thus receives general treat- 
ment, while that part of the body in contact with the 
electrode receives the greatest concentration of the 
current, and so gets local treatment. 
The condenser couch method, or " auto-condensation " 



170 ESSENTIALS OF MEDICAL ELECTRICITY 

method as it is sometimes called, therefore enables both 
general and local applications to be made, while the metal 
electrode under the couch obviates the necessity of fixing 
an indifferent electrode in contact with the skin each 
time the treatment is given. 

Another way of giving general applications of high 
frequency is to enclose the patient within a greatly 
enlarged solenoid. The patient stands or sits within 
the solenoid, the long axis of which is vertical. He does 
not come in contact with any part of it. His body is 
traversed by " eddy " currents that are induced within 
from the coils of the solenoid. This method of applica- 
tion is known as the " auto-conduction " method. 

There is a method of applying high frequency specially 
suitable for local applications. If one of the electrodes 
attached to one end of the solenoid is placed in contact 
with the body and the other (the active) electrode be 
brought near to the skin without actual contact, a dis- 
charge of sparks will take place across the intervening 
space. If the active electrode terminates in a metal 
point or group of points, the discharge takes the form of 
a brush of very fine sparks or " effluve." To procure 
an efficient eftiuve it is necessary to have a considerably 
higher voltage between electrode and skin than that 
reached between the extremities of the solenoid. By 
connecting to one end of the solenoid an additional coil 
of wire, and attaching the active electrode to the free 
extremity of this coil, the voltage will be considerably 
raised. This additional coil is known as " Oudin's 
resonator." It is shown in Fig. 48, where it is seen 
mounted vertically on the top of the trolley, partly 
enclosed in an insulating cover. 

It consists of a wooden cylinder or cage about nine 
inches in diameter, and fifteen to eighteen inches high, 
and wound with about sixty turns of moderately coarse 
wire — the individual turns are about one quarter of an 



HIGH-FREQUENCY EFFLUVE 171 

inch apart and should be evenly spaced at all points. 
The lower end of this wire is joined to some part of 
the thick wire spiral (solenoid) of the high-frequency- 
apparatus, the best point being found by experiment. 
The upper end of the resonator terminates in a knob 
mounted on top of the instrument. The wire of the 
resonator acts as a continuation of the solenoid. It is 
possible to dispense with the latter and use the lower 
few turns of the resonator in its stead. If this is done, 
the lower (proximal) end would be connected to the outer 
coating of one jar, while the outer coating of the other is 
attached to a point a little higher up, changing it about 
until the best effect is produced. To the upper (distal) 
end of the resonator is attached an insulated cable and 
to the free end of the latter is secured the electrode. 
When the apparatus is set in action a profuse " brush 
discharge " or effluve is given off from the electrode. 
This effect is increased when one end of the solenoid — 
or, when this is not used, the lower end of the resonator 
winding — is connected to earth, by attaching it to a gas 
or water pipe. The length of the effluve depends upon 
the point along the spiral to which the outer coat of 
the second Leyden jar is connected, and a slight 
alteration in the position of this point may considerably 
increase the length of the effluve. 

For local applications, many forms of electrodes have 
been used. The simplest is what is called the brush 
electrode, and consists of a metal plate from one to three 
inches in diameter and studded on one side with a number 
of sharp metallic points or tufts of fine brass wires or 
tinsel : to this metal plate is attached an ebonite rod 
for the operator to hold. 

Other forms are made of closed glass tubes, either 
filled with some conducting liquid as water or saline 
solution, or exhausted until the partial vacuum produced 
becomes sufficiently conducting. They are sometimes 



172 ESSENTIALS OF MEDICAL ELECTRICITY 

caUed condenser electrodes, because the internal conduct- 
ing medium induces, when charged from the resonator, 
corresponding charges on the outside of the glass. 
/ The most generally used condenser electrodes are the 
so-called " vacuum " electrodes (Fig. 50). These are 
closed glass vessels of various shapes and sizes, from 
which the air has been sufficiently exhausted to render 
the residual gas as good a conductor as possible. One 
end of the tube is pierced by a platinum wire fused into 
its wall. To this wire is attached the cable from the 




Fig. 50. — Vacuum Electrodes 

resonator or solenoid. The other end of the tube is 
applied to the patient. When the current is turned on 
the air within the tube conducts the current and becomes 
incandescent, glowing with a violet-blue light. At the 
same time fine crackling sparks pass from the glass at 
the end in contact with the skin. The sparks are longer 
if the electrode is attached to the resonator than if it 
is attached to the end of the solenoid. 

Of all the ways of applying high-frequency currents, 
the local application of the current from the top of the 
resonator is perhaps the most successful. It may be 
applied in the form of a soft brush discharge from a 
multiple point electrode held just so far from the patient 
that actual sparks do not pass. There is a copious 



HIGH-FREQUENCY ELECTRODES 173 

production of ozone and the brush itself acts as a mild 
stimulant. Instead of this we may use a vacuum elec- 
trode which is of glass and placed in contact with the 
surface to be treated. The strength of the appHcation 
can be very gradually adjusted, and, speaking generally, 
it is more stimulating than the brush. 

In some of these electrodes the vacuum is so high that 
X-rays are given off in small amount, but it is doubtful 
if such rays exist in sufficient quantity to have any 
effect. 

The appUcation from a vacuum electrode can be 
made so strong as to be decidedly painful and produce 
blistering if kept on too long. If such vigorous treat- 
ment as this is required it is better to use a plain metal 
point electrode, owing to the fact that the glass electrodes 
tend to become pierced under such conditions, and so 
rendered useless. 

In use the metal point is held a little way off the 
surface to be treated, so that the spark has to jump 
across a gap the length of which is limited by the strength 
of the current employed. The rule is, the farther the 
point from the skin the more severe and painful is the 
effect. 

If the point is held very close and a strong current 
turned on, the local effect seems to be to a great extent 
a thermal one and a small blister quickly forms — as 
we withdraw the point the character of the discharge 
changes, becoming more intermittent, more painful and 
disturbing to the patient, and the effect seems to influence 
the tissues some distance down — superficial muscles are 
thrown into contraction and the skin takes a " goose 
skin " appearance — later on the part becomes red and 
blisters form. 

This method can be carried out by any high-frequency 
arrangement and wiU be found very useful in the treat- 
ment of warts, acne vulgaris, and port wine marks. 



174 ESSENTIALS OF MEDICAL ELECTRICITY 

The Action of High-Frequency Currents on the Body. — 

High-frequency currents produce none of the sensations 
that are customarily associated with the passage of 
electrical currents. Although the high-frequency current 
may reach a magnitude of 500 milliamperes or more, 
there is no contraction of muscle, no perception of pain 
or tingling. The only sensation that is apparent is 
warmth, and this is, as a rule, sHght and not immediately 
perceived. 

We have now a satisfactory explanation of this appar- 
ently anomalous behaviour of electrical currents when 
they oscillate at an extremely high rate, and the matter 
has been considered in Chapter I., dealing with the 
mode of action of electricity on the body. It may be 
mentioned here that it is the movement of ions caused 
by the current that constitutes the electric stimulus and 
that the high-frequency current oscillates to and fro at 
a rate so high that the ions are unable to keep pace with 
it. There is therefore no movement imparted to them 
by the current, so that the latter is unable to stimu- 
late the tissues. High-frequency currents can, however, 
bring about physiological and therapeutic effects, and 
the question arises, " What is the mode of action of these 
currents in bringing about the effects observed ? " Most 
probably by the production of heat. There is an actual 
sensation of heat in the skin, and it may be measured by 
a surface thermometer. The heat becomes greater as 
the area of contact between the electrode becomes 
smaller, thereby increasing the density or "concentra- 
tion " of the current at its entry, and it may actually cause 
a burn if the electrode has the form of a wire or needle. 
The development of heat within a conductor by an 
electric current in proportion to the resistance of the 
conductor and the square of the strength of the current 
is a well-known physical law (Joule's law). In the case 
of high-frequency currents and the body, we have a 



HIGH-FREQUENCY CURRENTS 175 

conductor of sufficiently high resistance and a current 
of sufficient strength, and when the current traverses the 
tissues heat is developed along its path, both on and 
within them. The development of heat on the tissues, 
" epithermy," can be readily demonstrated. The de- 
velopment of heat through the tissues, " diathermy," 
is less easy to demonstrate, as the currents produced by 
the commonly used d'Arsonval type of high-frequency 
machine are not very strong, and its density diminishes 
as it penetrates the tissues. But it is a necessary con- 
sequence of Joule's law that heat should be developed 
within the tissues as well, and it can be shown when 
stronger high-frequency currents (as generated by the 
diathermy apparatus described in the next chapter) are 
used. 

High-frequency currents have for the past twenty 
years been used empirically, with varying degrees of 
success for many maladies. When this form of electrical 
treatment is to be appUed, its mode of action by the 
production of heat on and within the tissues should be 
borne in mind, and the question of the advisability 
of its application and of the Ukelihood of benefit re- 
sulting should be considered from the same point of 
view. 

High-frequency currents have the effect, when the 
whole body is brought under their influence, of increasing 
the metabolic changes. D'Arsonval showed that there 
was an increase in the output of carbon dioxide, of nitrogen 
and phosphates in the urine, and an increased output of 
heat. This is what might be expected to follow a gentle 
warming of the tissues. High-frequency currents have 
an influence on the vascular system. Sloan found that 
their first action was to produce a peripheral vaso- 
dilatation. The heart then beat more rapidly and 
counteracted the tendency to fall of blood pressure 
produced by the vaso-dilatation. 



176 ESSENTIALS OF MEDICAL ELECTRICITY 

When local applications are made with the vacuum 
electrodes, no sensation other than that of heat is pro- 
duced, if the glass is in contact with the skin ; when it is 
placed a short distance away, numbers of sparks leap 
across and produce a pricking sensation. The skin soon 
acquires a vivid erythema, and if the application is for 
more than a short time in one situation localised burning 
may result, especially if the current is strong. The 
application of the effluve produces the feeling of a warm 
breeze, which may become uncomfortably hot when the 
electrode is placed near to the body : if brought very 
close, sparks will pass and cause pain. The effluve also 
produces an erythema of the skin. The stimulation of 
the skin and the erythema are the result of heating of 
minute points on which the effluve or sparks fall. There 
is at the same time a production of ozone and oxides 
of nitrogen from the atmospheric gases. These gases 
penetrate for a short distance into the outer skin layer, 
or they may possibly be formed there. Their odour is 
perceived for a considerable time afterwards. 

The therapeutic action of this local appUcation of high 
frequency is probably the result of local heating and the 
resulting hyperaemia. Possibly the new gases formed 
may have some action, particularly when the treatment 
is applied to infected ulcers and to cutaneous affections, 
such as acne and sycosis and others. 

High-Freauency and Surgical Cases. — ^It has been 
mentioned that the high-frequency sparks may produce 
destruction of the skin. They are actually used for the 
destruction of abnormal tissue. Metallic electrodes are 
used and sparks are directed from them on to the part 
to be treated. The destruction is brought about by the 
heat at the points on which the sparks fall. The tissue 
to be destroyed must be superficial and mlist not extend 
deeply. This form of treatment has been used with 



FULGURATION 177 

success for flat naevi, moles and warts, and it has proved 
successful in some cases of lupus and rodent ulcers. 
Malignant growths have also been treated by long high- 
frequency sparks from powerful apparatus ; the name 
of " fulguration " has been given to such treatment. 



CHAPTER XII 

DIATHERMY 

In the preceding chapter it was pointed out that the 
high-frequency current provided by the d'Arsonval type 
of apparatus was intermittent — that is to say, the oscilla- 
tions occurred in groups, each separated from the preced- 
ing one by a long interval during which there was no 
current. It was shown that the time occupied by each 
group of oscillations was very short, while the interval 
between each group was relatively very long, so that 
during any period of treatment the body was under the 
influence of the high frequency for only a very short 
fraction of the time. 

During recent years new types of apparatus have been 
designed for the purpose of producing high-frequency 
oscillations that are continuously kept up and not inter- 
mittent. With a current of continuous high-frequency 
oscillation the sensation of heat which, with the inter- 
mittent oscillations was slight or even imperceptible, 
becomes very pronounced and may be unbearable. The 
heat is developed along the path of the current, both in 
the superficial and deep parts. In recognition of this 
production of heat through the tissues as the essential 
action of sustained high-frequency currents on the 
body the word " diathermy " has been devised to 
describe this mode of electrical treatment. It may be 
said that all high-frequency currents produce some degree 
of diathermy, although the heat may not be perceptible 
or measurable. " High-frequency " treatment, as gener- 
ally understood, refers to treatment by the intermittent 

178 



PRODUCTION OF DIATHERMY 179 

high-frequency current produced by the d'Arsonval type 
of apparatus, and the term " diathermy " is reserved 
for treatment by continuous high-frequency oscillations 
producing heat as the most conspicuous effect. Whether 
the high-frequency currents are intermittent, producing 
a trifling amount of heat, or continuous, producing a large 
amount, the therapeutic action, in both cases, is due to 
the same effect — viz. the production of heat on and 
within the tissues. 

Diathermy has also been called " thermo-penetra- 
tion " and " transthermy," terms which also express the 
result of the action of sustained high-frequency currents 
of sufficient intensity. 

The Production of Continuous High-Freauency 
Currents. — ^These currents are generated on the same 
principle as the intermittent high-frequency current, but 
the various parts of the apparatus are modified. Instead 
of Leyden jars, the condensers are made of several sheets of 
metal separated and insulated from each other by glass 
or paper soaked in paraffin wax. These condensers have 
a larger capacity than the two Leyden jars used in the 
d'Arsonval apparatus. They are charged from the 
main, not from an induction coil. The positive and 
negative cables from the main are not connected 
directly to the condensers, because the latter would 
then be charged only to the voltage of the main supply, 
and this, at its highest, is not sufficiently high for the 
condensers. The voltage has therefore to be raised. 
This is done by means of a static transformer. The 
static transformer is described in detail on page 294, but 
we may say here that it consists of two coils of insulated 
wire, both wound on the same iron core, but separately 
and not in connection with each other. One coil, the 
primary, is made of a few turns of stout wire. The 
secondary is made of several turns of finer wire. The 



i8o ESSENTIALS OF MEDICAL ELECTRICITY 



current from the main is led through the primary. 
Currents are induced in the secondary, and their voltage 
and amperage will depend on the number of turns in 
the latter. The voltage is raised to about 2000. The 
current from the main must be an alternating current, 



PriT»La.ry coil 0^ Tra-ns|-ormer 
Setondary CO»l oj Transjornrver 



ill 



St>ark <^ap 



■ i 



CoacLe.nsers 



Higti jreoi/enc^ Circuit 

High jrt(^enty Circud 
(Steondoryj 



» 6 ^O 30 

Terminals ^o Patient 
Fig. 51. — Diagram showing Circuits in a Diathermy Apparatus 

because a direct current passing through the primary 
would not induce currents in the secondary. If the main 
supply happens to be a direct current, it must first be 
transformed into an alternating current by means of a 
motor transformer. The current that is supplied to the 
primary of the transformer may reach, say, lo amperes, 
and the voltage at which it is supplied from the main 



DIATHERMY MACHINE CONSTRUCTION i8i 

is 100. The latter is raised to 2000, and to this voltage 
the condensers are charged. Now in the d'Arsonval 
apparatus there is a transformer (viz. the induction coil 
with its iron core, and primary and secondary windings), 
but the current is treinsformed to a much higher voltage, 
30,000 volts or more, which is unnecessarily high. 
Further, the primary of the induction coil is supplied by 
a current of less amperage, and, being a direct current, 
must be interrupted. It will therefore flow inter- 
mittently. Consequently there will be a smaller amount 
of electric energy supplied to the primary of an induction 
coil by the direct current than to the primary of a trans- 
former by the alternating current. 

The different circuits in the diathermy apparatus are 
shown diagrammatically in Fig 51. The condensers 
are charged from the secondary of the transformer. 
They discharge across the spark-gap and the solenoid is 
traversed by high-frequency currents. The spark-gap 
is quite different from that used in the d'Arsonval 
apparatus. The discharge takes place, not between 
two metal rods, but between large metal discs that are 
very closely opposed to each other without actually 
touching. There are two of these gaps placed in 
series. The discs are made of copper and their 
opposing surfaces, between which the sparks leap, are 
faced with silver. Each gap is about 0-4 millimetre 
wide. 

The high-frequency current that is to be applied to the 
patient is taken, not from the solenoid directly, but from 
another separate coil that can be placed in close apposi- 
tion with it, and so receive high-frequency currents 
by induction. This latter coil is the secondary high- 
frequency coil. A hot-wire ampere-meter is included in 
the circuit containing the patient and the latter coil. 

When an alternating current from the main is supplied 
to the primary of the transformer, the condensers are 



i82 ESSENTIALS OF MEDICAL ELECTRICITY 



charged and discharged at an extremely rapid rate, far 
more rapid than that at which the Leyden jars in the 
d'Arsonval apparatus are charged and discharged. The 

discharge across 
iflHIE y^^ 4HHHIHE the spark-gap 
^^^^B: J^W^ ^mmi ^^|P causes a crack- 
jBB^^^ rr^jH^HI ^HBi ling, hissing 
WKf mt^^mKEik sound. The 

* ** j_ sparks are, as it 

were, spread out 
over a large area, 
and instead of the 
bright, white, 
noisy sparks seen 
in the gap of the 
d' Arson val ap- 
paratus, a film 
of non-luminous 
blue light occu- 
pies the narrow 
gap between the 
opposing metal 
discs. If wires 
connected to the 
extremities of the 
secondary high- 
frequency coil are 
brought close to- 
gether a torrent 
of thick, white, 
noisy sparks 
passes between 
them. 

A diathermy machine by A. E. Dean is shown in 
Fig. 52. The transformer, condenser and high-frequency 
coils (primary and secondary) are enclosed within the case 




Fig. 52 
Diathermy Machine by Dean 



PHYSIOLOGICAL ACTION OF DIATHERMY 183 

that forms the body of the machine. The cover of the 
case is formed by a marble slab, on which are fixed the 
ampere-meter, the spark-gap, the handles for regulating 
the currents, a switch for cutting off the current supplied 
to the machine and terminals for leading the diathermy 
current to the patient. The spark-gap is covered by a 
U-shaped metal cage, so as to protect the operator from 
burns which might be caused by accidentally touching 
the metal discs. 

Other models of diathermy apparatus have been de- 
signed. They all work on the same general principle 
and differ chiefly in the method adopted for regulating 
the strength of the current and in the construction of 
the spark-gap. In the machine illustrated the high- 
frequency current is regulated by bringing the secondary 
high-frequency coil more or less closely in apposition 
with the solenoid. This is effected by rotating the handle 
shown on the right-hand side of the marble slab. A 
crank, shown on the left-hand side, regulates the amount 
of current supplied to the transformer and so increases 
or diminishes the output of the machine. In other 
machines the current supplied to the transformer is 
regulated by means of a variable resistance that is in- 
cluded in series with the primary coil ; while in some 
machines the high-frequency current to the patient is 
regulated by taking a varying number of turns of the 
secondary high-frequency coil into circuit. 

Physiological Action of Diathermy. — The sustained 
high-frequency currents supplied by the diathermy 
machine raise the temperature of the tissues which they 
traverse, and such physiological effects that have been 
observed to follow applications of diathermy are the 
result of this rise of temperature. The subject has not 
yet received much experimental investigation. Rechou 
made some observations on the respiratory exchange of 



i84 ESSENTIALS OF MEDICAL ELECTRICITY 

a subject during the application of diathermy (quoted by 
Bergonie, Archiv. d' Elect. Med., loth March 1913). He 
found that the first effect of the diathermy was to 
increase the intake of oxygen and output of carbon 
dioxide. As the diathermy continued it was foimd that 
the subject took in less oxygen and gave out less carbon 
dioxide. The first effect of the diathermy was to 
increase metabohsm, evidently that concerned in the 
production of heat ; the second effect was to diminish 
it, the artificial introduction of a large quantity of heat 
rendering unnecessary the production of the customary 
amount of heat by the body. 

The application of general diathermy to the normal 
subject by means of electrodes grasped by the hands or 
embracing the forearms is followed by a sensation of 
heat. The heat is felt first in the narrowest part of the 
forearm ; it then spreads up the arms ; afterwards the 
whole body feels warmer, but the greatest heat is always 
felt in the lower part of the forearm, where the path for 
the current is narrowest and the resistance therefore 
greatest. The subject sweats profusely after the dia- 
thermy has been in progress for some minutes, more 
especially from the upper limbs and face, when the 
electrodes are applied to the forearms or hands. The 
frequency of the pulse rises and, in some subjects, the 
blood pressure falls. Occasionally the fall is accom- 
panied by a feeling of faintness and the diatherrriy must 
then be stopped. 

Proof oi the Heating of the Deep Parts. — ^Experiments 
on animals have been carried out by various workers, 
and they show that the heat produced by the diathermy 
penetrates into the deep parts and is not confined to the 
skin. Thus the hind limbs of animals have been coagu- 
lated in their entirety. Electrodes have been placed on 
the exterior of an animal's skull and the diathermy 



APPLICATION OF DIATHERMY TO BODY 185 

current passed through the brain. A thermometer with 
its bulb in the lateral ventricle showed, in one experiment, 
a rise of 1° centigrade after ten minutes' diathermy. 

In the human subject investigation of the subject is 
more difficult. The author was able to show, in one 
case, a rise of temperature of i'2° F. in the posterior 
fornix vaginae after appUcation of diathermy to the 
pelvic region by way of electrodes placed over the 
hypogastrium and under the gluteal region. 

How Diathermy is applied to the Body.— Diathermy 
may be apphed so as to raise the temperature of the 
whole body (general diathermy), or of part of it (local dia 
thermy). The passage of the diathermy current through 
any part heats not only the fixed tissues, but also the 
blood that circulates through them, so that if the applica- 
tion of the current is for long, and particularly if a large 
part of the body is traversed by the current, the tempera- 
ture of the rest of the body will be raised by means of the 
heated blood. Therefore the local treatment becomes, 
to a greater or lesser degree, a general treatment as well. 

(a) General Treatment. — ^This may be given on a 
special form of condenser couch. It was designed by 
Schittenhehn, and is shown in Fig. 53. The patient Ues 
on sheet ebonite one-eighth of an inch thick, placed on 
the framework of the couch. Under it lies a large metal 
sheet divided into four separate parts. One Hes under 
each lower extremity and one under each shoulder and 
corresponding side of the trunk. The cables from the 
diathermy machine are connected to two terminals at 
the head of the couch. A ** changing box " is fixed to the 
head of the couch. In it are enclosed five cranks, and 
each of the four parts of the metal sheet is connected to 
one of these. By turning these cranks into the appro- 
priate positions it is possible to connect either cable from 
the diathermy machine with any division or divisions of 



i86 ESSENTIALS OF MEDICAL ELECTRICITY 

the metal plate. Suppose that one cable is connected 
to the division under the right shoulder, the other to the 



mm 



ff 


F"l 


IB 




— ^fi 




\^ 


11 


to 


l] 


1= 


6 




II 






Ph 









division under the right lower limb. Each division will 
then become alternately positively and negatively 



LOCAL DIATHERMY TREATMENT 187 

charged, the frequency of the alternation of the charge 
corresponding to the frequency of the oscillation of the 
diathermy current. Charges will be induced on the parts 
of the body in contact with the ebonite sheet over the 
metal plates. These induced charges will change their 
sign synchronously with the inducing charges. Conse- 
quently induced currents will oscillate through the body 
between the right shoulder and the right lower limb. By 
suitable arrangement of the cranks in the changing box 
the currents may be made to oscillate between shoulder 
and shoulder, or between both shoulders and both lower 
limbs, or in any other direction. 

When applying diathermy on the condenser couch the 
patient need not remove clothes, but metal, such as coins 
or keys in the pockets, and watch and chain, are best 
removed, also corsets, if they contain metal. He 
gradually experiences the sensation of warmth, and it 
is first felt in the parts in contact with the couch. A 
watch should be kept on the pulse and blood pressure, 
for occasionally the latter falls and the patient feels 
faint. The treatment must then be stopped, 

{b) Local Treatment.' — The part to be treated is 
enclosed between two electrodes placed on opposite sides. 
In the case of limbs, they may be placed above and below. 
The electrodes are made of metal plate, and are of 
different sizes and shapes, oblong, square or circular. 
They should roughly approximate in size and shape to 
the part to which they are applied. The metal plates may 
be placed in direct contact with the slightly damped 
skin, or an absorbent pad about one-fourth of an 
inch in thickness, soaked in salt solution, may be inter- 
posed. With the latter device a better contact may be 
ensured when the surface is irregular. Tap-water must 
not be used to soak the pads with, as it does not contain 
sufficient saline substances in solution (ions) to conduct 
the current readily. If used, the electrodes become 



i88 ESSENTIALS OF MEDICAL ELECTRICITY 

gradually hotter and may cause burns. The strength of 
the salt solution should not be less than io%. 

When the electrodes are securely bandaged in position 
the current is turned on and gradually increased till the 
patient begins to perceive warmth. The warmth gradu- 
ally increases and the current may be afterwards further 
increased till the heat is as much as can be borne without 
discomfort. The patient's sensation is a sufficient guide 
to ensure diathermy without burns, but if there is 
anaesthesia, diathermy cannot be applied without some 
risk. Nagelschmidt has composed a table showing the 
maximum current that can be safely borne by the skin 
with different size electrodes. The latter must make the 
best possible contact with the skin and the current should 
not be applied at once in the maximum permissible 
strength. 

Local treatment may also be given on the condenser 
couch. A terminal on the changing box is connected to 
an electrode that is placed on the part requiring local 
treatment. By means of one of the cranks in the chang- 
ing box this is brought into connection with one of the 
cables of the diathermy machine. The other cable is 
brought into connection with one or more of the metal 
plates under the ebonite sheet. By this method the part 
requiring local treatment will be very effectively heated, 
while, at the same time, the other parts will receive a less 
intense but more general treatment. This method is 
particularly suitable when a large portion of the body, 
such as the chest or abdomen, is to be subjected to 
diathermy. 

In the absence of a condenser couch, general treatment 
may be given by applying two electrodes, one to each 
forearm. The current therefore passes along the arms, 
across and between the shoulders. In this way the 
temperature of the arms is raised, while the heated blood 
passes to the rest of the body and gradually raises its 



MEDICAL DIATHERMY 189 

temperature. Electrodes may then be applied to the 
legs, so that the current passes along them and across the 
pelvis, producing local and general heating as before. 
The current may be directed simultaneously from arm 
to arm and from leg to leg, by attaching electrodes to 
each part and using double or bifurcated cables. 

Special electrodes are made for diathermy of special 
parts. Metal tubes with closed, rounded ends are used 
for insertion into rectum or vagina. Vacuum electrodes, 
the same as used for high frequency, may also be used 
for local application, so as to combine the action of the 
diathermy with that of the ozone and oxides of nitrogen. 
These electrodes are described in the preceding chapter. 

Medical Diathermy. — The appUcation of diathermy to 
medical cases has not been practised long enough in this 
country to allow a definite statement of the morbid con- 
ditions for which it is to be applied. Maladies and 
morbid conditions that are likely to benefit from applica- 
tion of heat, are likely to improve further by diathermy. 
Heat as ordinarily applied waxms the skin only. The 
sustained high-frequency current heats the deep parts 
as well as the superficial, whereas other methods produce 
only surface-heating or "epithermy." Inflammation of 
nerves, joints and serous membranes, accompanied by 
pain, are often reUeved by diathermy. Diathermy seems 
to be very successful for cases of gonorrhoeal arthritis. 
The gonococcus is apparently sensitive to small rises of 
temperature. By the diathermy current the joint is 
heated through. 

The temperature of the whole body can be raised by 
general diathermy, and brought into a state of " physio- 
logical fever." The condition of lowered vitality, in 
which there is depression of the functional activity of 
the organs — cases to which the name "misere physio- 
logique " has been appHed — ^are much benefited by general 



I90 ESSENTIALS OF MEDICAL ELECTRICITY 

diathermy, which suppHes the heat that the body can- 
not supply, in its state of impoverished vitahty. Nagel- 
schmidt claims that diathermy can lower abnormally 
high blood pressures. He applies one electrode to the 
precordium and another to the back. Angina pectoris 
is said by the same writer to benefit by similar treatment. 

Surgical Diathermy. — ^By means of the diathermy 
current it is possible to raise the temperature of the 
tissues sufficiently high to destroy their vitahty. They 
can be coagulated in situ. The diathermy current 
can therefore be used to destroy new growths, both 
innocent and malignant. The coagulation is due to the 
heat that is produced within the tissues as the current 
traverses them. Such instruments as the galvano- 
thermo-cautery and the Paquelin cautery simply char 
the tissues locally, and, as the latter conduct heat very 
badly, there is very httle spread of coagulation beyond 
the carbonised cavity. The tissues conduct electricity 
well, and, as it is the electricity that develops the heat, 
there is not this limitation to the spread of the coagula- 
tion. It is therefore easy, by means of the diathermy 
current, to coagulate a malignant growth in its entirety 
" through and through." 

The rise of temperature necessary to coagulate a 
growth is brought about by reducing the size of the 
electrode in contact with the growth (the active electrode) 
to that of a needle or small disc or button. The other 
electrode (the indifferent electrode) covers a large area 
of skin. The current density will be greatest at the 
point where the current leaves the electrode to enter 
the tissues, and there the temperature will reach the 
highest. As the distance below the surface increases, 
so the current density lessens and the temperature 
diminishes. For a certain distance below the electrode 
the tissue is coagulated. 



ELECTRODES FOR SURGICAL DIATHERMY 191 

The depth to which coagulation spreads depends, 
apart from the time during which the current flows, upon 
the shape and size of the active electrode and the vascu- 
larity of the tissue. The larger the surface of contact 
between the active electrode and the tissue, the greater 
will be the depth to which coagulation will extend. If 
a small surface electrode is used the current density is 
great at the point of contact with the skin, and the 
temperature there very quickly rises to a point at which 
the tissue is dried. Dried tissue conducts the current 
badly and sparks make their appearance and the current 
has to be switched off soon after it is started, so that 
there is no time for the coagulation to spread far. The 
depth to which coagulation spreads depends also on the 
vascularity of the tissue. The circulating blood tends 
to dissipate the heat and may prevent coagulation in the 
region where the temperature would be, in less vascular 
tissue, just sufficient to cause it. As an approximate 
guide, it may be taken that the coagulation will spread 
below the electrode for a distance equal to the diameter 
of the latter. 

Electrodes. — The most generally used active electrode 
consists of a short rod-shaped ebonite handle with a 
metal core. Into the proximal end of this is screwed one 
of the cables leading to the diathermy machine. To the 
distal end is attached a metal end-piece. The latter is 
usually a disc or button, bearing sometimes one or more 
short metal spikes. Special end-pieces have been 
designed for less accessible regions, such as the larynx 
and oesophagus. The indifferent electrode is composed 
of a pad of lint or folded towel measuring 12 inches by 
8 inches. It is soaked in strong salt solution and placed 
on the chest or abdomen. On it is placed a piece of 
sheet lead one sixteenth of an inch thick and 8 inches 
long and 6 inches broad, and to it is connected one of 
the cables from the diathermy machine. 



192 ESSENTIALS OF MEDICAL ELECTRICITY 

How Surgical Diathermy is performed. — ^An anaesthetic 
is required except when very small portions of tissue 
have to be destroyed and the applications are momen- 
tary. A general anaesthetic is required if the tissue to 
be destroyed Ues in a less accessible region, such as the 
mouth and throat, and if a large mass of tissue has to 
be destroyed. A local anaesthetic may be used in some 
cases. The electrodes axe placed in position, the in- 
different electrode on the chest or abdomen, the active 
electrode on the growth. The current is then switched 
on and gradually increased. Bubbles of gas are seen 
escaping from the region of the active electrode and the 
tissue under the latter whitens from coagulation. The 
current is then switched off and the electrode placed 
on an adjoining part. The current need not be further 
adjusted, but it is merely switched on till coagulation 
has again taken place. In this way the whole of the 
growth is coagulated. If the growth is fungating it may 
be necessary to gently scrape off the coagulated tissue 
and coagulate further till it is thought that healthy 
tissue has been reached. 

Advantages of Diathermic Coagulation or Cautery. — 

The operation is quick and patients do not suffer from 
shock after it. They are able to get up after forty-eight 
hours in most cases and leave hospital in a few days. 
The blood vessels and lymphatics are sealed by the 
coagulation of their contents. Oedema of the surround- 
ing parts comes on during or soon after the operation 
and a copious discharge of lymph sets in and lasts some 
hours. The coagulated tissue sloughs away and the 
cavity quickly fills with granulation tissue. A point of 
special interest is the absence of adhesions at subsequent 
periods. 

Results. — ^Diathermy has been used of late for the 
treatment of inoperable malignant growths. Many of 



RESULTS OF SURGICAL DIATHERMY 193 

these have been made to disappear, and although re- 
currence takes place, this event has in many cases been 
postponed for a year or even longer. One patient with 
an inoperable growth of the tonsil and fauces lived as long 
as two years and nine months after the first application 
of diathermy. It is always necessary to keep the cases 
under observation and reapply the diathermy when 
recurrence is noticed. The patient referred to had six 
appUcations. Other cases show recurrence at an earher 
date, but considerable improvement is the rule, and the 
relief from distressing symptoms, such as pain, discharge 
and constant expectoration when the growth has involved 
the mouth and throat, is a common occurrence. 

Diathermy would give its best results in the treatment 
of operable growths. There is no reason why removal 
with the knife should not follow diathermy, as the 
destruction of the main mass of the growth and the seal- 
ing of the blood vessels and lymphatics would minimise 
chances of dissemination. 

Diathermy has also been tried for non-mahgnant 
growths. It has given good results in cases of large 
naevi. Naevi of the mucous membranes are more suitable 
than naevi of the skin. For papillomata of the bladder 
it would seem the treatment far excellence. Each 
papilloma is in turn brought into view by the cystoscope 
and an insulated wire is passed along the channel in- 
tended for the catheter to the ureter. It makes contact 
with the papilloma and the current quickly coagulates 
it.i 

* For a more complete account of diathermy see Archives of the 
Roentgen Ray, July, 19 14, et seq. 



CHAPTER XIII 

THE USE OF STATIC ELECTRICITY 

Apparatus required. — ^The first requirement is a gener- 
ator of static electricity, or, as it is called, a " static 
machine." The old frictional generator has been long 
discarded and its place has been taken by the so-called 
"influence machines." There are two principal kinds, 
the Holtz machine and its modifications and the 
Wimshurst machine. 

The Holtz machine is very popular in America, but it 
possesses at least two distinct disadvantages. It has 
first to be given an initial charge from a smaU Wims- 
hurst before it wiU start generating, and it is also 
sensitive to the changes of the weather. 

The Wimshurst Machine is self-exciting and has no 
tendency to reverse during action, and on this account is 
most popular in this country. With some machines of 
this type one can never be sure beforehand which pole 
will be positive and which one negative, but once started 
the polarity will not change during the continuance of the 
run. It is not so sensitive to changes of the weather. 
In very damp weather, if it is not enclosed in an air-tight 
case, its output will be reduced and it will not be self- 
exciting. Fig. 54 shows a small Wimshurst. 

It consists in its simplest form of two circular glass 
plates, each mounted on the end of a hollow boss of wood 
upon which a groove is turned to act as a pulley for 
driving the plate. The wooden bosses with the plates are 
mounted in a horizontal steel shaft, so that the plates are 

194 



WIMSHURST MACHINE 



195 



facing each other and about one-eighth of an inch apart. 
Directly below the plates is another horizontal shaft, 
upon which are secured two large wooden pulleys exactly 
oppccite the grooves turned on the wooden bosses. A 
handle is provided at one end of the lower shaft, and two 
leather belts, one of which is crossed, are fitted round each 
pulley and its corresponding boss. When the handle is 
turned the plates will revolve in opposite directions. 
The plates are well varnished, and attached to their 
outer surfaces are a 
number of radial sectors 
of tin-foil or thin brass. 
These are equally spaced 
all round the discs — ^they 
make the machine more 
easily self-exciting, but 
are not essential to its 
action, especially in the 
case of larger machines. 
By means of a neutral- 
ising rod tipped with a 
fine wire or tinsel brush 
at each end, mounted so 
as to be adjustable con- 
centrically with the shaft 
upon which the plates revolve, each pair of sectors at 
opposite ends of a diameter are placed momentarily in 
metallic contact twice during each revolution. These 
neutralising rods must be adjusted to the point of maxi- 
mum efficiency, which will be readily found by experiment . 
If we stand facing the plate, and its direction of rotation 
be clockwise, the neutralising rod will be in the position 
of the hands of the clock indicating five minutes to five. 
This will vary in different machines, but the correct 
position will be found very near this point. The fixed 
conductors are moimted at the ends of the horizontal 




Fig. 54. — Wimshurst Machine 



196 ESSENTIALS OF MEDICAL ELECTRICITY 

diameter and consist of two forks, with collecting points 
on the inside pointing towards each other, and the plates 
revolving between. These forks are mounted on ebonite 
or glass pillars, and to each fork is attached an electrode 
consisting of a metal rod bearing a brass ball at one end 
and an ebonite handle at the other. The electrodes are 
movable, and an operator can grasp the insulating 
handles and move the electrodes, so that the brass balls 
can be brought closer together or farther apart. The 
collecting device with the discharging apparatus is some- 
times called the " prime conductor." When the plates 
are revolved, positive electricity collects on one electrode, 
negative on the other. If the electrodes are sufficiently 
close together a succession of fine crackling sparks passes 
across the intervening gap. With a large machine the 
sparks may be many inches long. The difference of 
potential between the charges on the two electrodes 
reaches a very high value. 

As usually supphed, the machines have a Leyden jar 
attached to each electrode, the latter being connected 
to the inner coating of the jar. When their outer coatings 
are connected together and the machine set in action the 
character of the discharge is completely altered. Instead 
of the soft crackling brush, the discharge takes place at 
definite intervals and each is accompanied by a more or 
less loud report. 

The Leyden jar greatly increases the capacity of the 
electrodes, so that they can take much larger charges, 
but a longer time elapses before these larger charges 
reach a potential sufficiently high to overcome the 
resistance of the air between them. A loud, intensely 
white, thick spark accompanies the discharge. 

A shock from a large machine with the jars connected 
might be fatal. The jars are, in most cases, to be dis- 
connected before any static machine is used for treating 
patients. 



WIMSHURST MACHINE 197 

There are made by some manufacturers various 
modifications of the Wimshurst. One has ebonite 
plates, and, on account of the toughness and flexibihty 
of the material, the plates can be driven at a very high 
speed. Another has plates made of compressed mica, 
which can also be driven at a high speed. The advan- 
tage of high speed is that the same difference of potential 
can be obtained with a smaller plate, making the machine 
less bulky. The disadvantages of ebonite are that it 
often becomes bent and buckled out of shape. Also its 
insulating properties become very much impaired after 
a time, and the output of the machine correspondingly 
reduced. 

For medical purposes the Wimshurst machine should 
have not less than eight plates, thirty or thirty-six inches in 
diameter. The machine should be enclosed in an air-tight 
case with glass windows, so as to prevent the attraction of 
particles of soot and dust from the atmosphere. The air 
inside the case can be dried by desiccators, such as boxes 
of quicklime or trays of sulphuric acid. The machine 
is driven by a small electric motor, or a gas or oil engine. 

Glass coated with shellac is at present the most suit- 
able material for the plates. Ebonite is lighter, and 
plates made of this material can be driven at a higher 
speed than glass, so that electricity can be generated at 
a quicker rate. But ebonite deteriorates after a time, 
as chemical changes take place on its surface and impair 
its insulating properties. It loses its black colour and 
acquires a greenish tint. Further, it tends to warp, so 
that the plates come in contact as they revolve. 

The Wimshurst machine has the following advantages. 
As soon as the plates begin to revolve it begins to gener- 
ate electricity. The other machines will not generate 
electricity when the plates are made to revolve, unless an 
initial charge has been given to it first. The Wimshurst 
machine is less sensitive to damp than the others. 



198 ESSENTIALS OF MEDICAL ELECTRICITY 

The Holtz Machine. — In its simplest form this machine 
(Fig- 55) consists of two vertical glass plates, one of which 
(A) is fixed, while the other {B) can revolve parallel to it. 
The plates are close together, but do not touch. The fixed 
plate is shghtly larger than the revolving plate. In the 
fixed plate are cut two "windows " {a and b) diametric- 



FiG. 55. — Holtz Machine (from Electrical hifluence Machines^ 
by J. Gray) 

ally opposite each other. Two pieces of paper, known 
as " field plates," are fastened on to the fixed glass plate, 
one {d) being placed above the window (&), the other being 
placed below the window [a). A strip of paper attached 
to each of these field plates projects through the window 
on the same side and points at the revolving plate with- 
out touching it. The latter plate revolves in a direction 
opposite to that in which the strips point. Two metal 
rods {g and i), bearing metal spikes, collect the electric 



MODIFICATIONS OF HOLTZ MACHINE 199 

charges from the revolving plate on to the metal balls 
shown in the figure. Two of these balls, mounted on the 
ends of brass rods with insulating handles, are movable, 
and can be brought closer together or farther apart. 
They are made to touch when the machine is to be 
started. The rod tv, known as the " neutralising rod," 
carries a comb at each end, the points of which are 
directed towards the front of the revolving plate. 

To start the machine, an electric charge from a rubbed 
ebonite rod is given to one of the field plates. The 
movable plate is then revolved and the balls drawn 
apart. Sparks then dart across the gap separating them. 

The modern form has six or eight plates, arranged in 
pairs, each pair consisting of one fixed and one revolving 
plate. It is enclosed in an air-tight case and is driven by 
a motor like the Wimshurst machine. An initial charge 
of electricity must be administered to one of the field 
plates of the Holtz machine before the plates are made 
to revolve, otherwise no electricity will be generated. A 
very small Wimshurst machine is usually placed in the 
case to generate this initial charge. 

The Toepler machine (known also as the Voss machine) 
works on the same principle as the Holtz ; it is usually 
self-starting, requiring no initial charge. 

The Baker paper-disc machine is much used in 
America, and those who have used it in this country 
speak favourably of it. It is a modified Toepler machine. 
The stationary plates, four in number, are made of glass. 
The four revolving plates are made of paper. Each 
plate is composed of twenty-four discs of paper saturated 
in shellac and other gums, compressed together between 
hot metal discs. These plates are light, unbreakable 
and do not readily condense moisture on their surfaces, 
and so their insulating properties are not impaired. They 
can be rotated 2000 times per minute. The usual rate with 
glass plates is 350 per minute. The machine is enclosed 



200 ESSENTIALS OF MEDICAL ELECTRICITY 

in a case and driven by a motor. It requires an initial 
charge before it generates further quantities. A small 
Wimshurst machine is provided for the purpose. Out- 
side the case enclosing the static machine are the two 
prime conductors. The latter are fitted with sliding rods 
bearing a brass ball at one end and an ebonite handle at 
the other. The air space between the brass balls is the 
spark gap and its length can be regulated by the sliding 
rods. 

Static machines are usually provided with a pair of 
Leyden jars. One is connected with each prime con- 
ductor. In most methods of applying static electricity 
to patients they are not used and should be disconnected. 

Accessory Apparatus. — The accessory apparatus in- 
cludes an insulating platform, a set of electrodes, lengths 
of brass chain for connecting the electrodes to the prime 
conductors or to other parts where necessary, and a long 
brass rod bent to a hook at one end, like a shepherd's 
crook, for the purpose of connecting the patient to the 
machine. 

The insulating platform supports the patient. It is 
mounted on four stout glass legs. The legs should be 
coated with shellac to prevent the condensation of 
moisture on them, which would impair their insulating 
power. They should be at least ten inches long. When 
powerful machines are used, the platform should be 
raised thirteen inches off the ground by its insulating legs. 
The wooden framework should have all corners and edges 
rounded off. The platform should be large and strong 
enough to support the heaviest patient. It should 
measure 5 feet by 2 feet 4 inches. The patient sits on 
a chair on the platform. The chair should contain no 
metal, and all edges should be rounded off. The patient 
must sometimes be in a reclining position. When this is 
necessary, the chair should be replaced by a wicker couch. 



ELECTRODES FOR STATIC MACHINE 201 

Four common types of electrode are shown in Fig. 56. 
Each consists of an ebonite handle with a metal end- 
piece. The latter may be a metal rod, tapering to a point, 
or it may terminate in a metal disc bearing a number of 
metal spikes. These are known as the single-point and 
multiple-point electrode respectively. The metal may 
terminate in a brass ball (ball-electrode) or may carry a 
metal roller (roller electrode) . The metal portion of each 



1 




Fig. 56. — Electrodes for use with Static Machine 

1. Single-point (metal) electrode 

2. Multiple-point (metal) electrode 

3. Metal ball electrode 

4. Roller electrode 

electrode bears a small metal ring, to which may be 
attached the brass chain connecting it to the machine. 

These electrodes have been modified in various ways. 
Thus, the handle may be made of some partially con- 
ducting material, such as wood that can absorb a certain 
amount of moisture. It may terminate in a metal or 
wooden point. The chain that connects this electrode 
with the static machine is attached, not to the metal end, 
but to a short length of metal tube that slides over the 



202 ESSENTIALS OF MEDICAL ELECTRICITY 

handle, and its position can be adjusted so as to include 
a greater or smaller length of wood between it and the 
tip of the electrode. This electrode has been used 
especially for the application of the static breeze (see 
below). 

The Machine in Action. — When the motor is started and 
the plates are revolving, positive electricity collects on 
one prime conductor, negative on the other, and when 
the sUding rods are brought towards each other sparks 
pass between them with a frequency that increases the 
closer the rods approach one another. 

It is necessary to know the prime conductor on which 
the positive and on which the negative electricity accumu- 
lates, because each time the machine is started the same 
prime conductor does not invariably charge up the same. 
A convenient way to "test the polarity," as it is called, 
is to proceed as follows. Start the machine and bring the 
single metal point electrode gradually nearer to one or 
other of the prime conductors. The point electrode 
should be connected to earth by a chain attached to the 
ring on the metal part of the electrode, and at the other 
end to a water or gas pipe, or the floor of the room if 
of wood or stone. Gradually bring the point of the 
electrode nearer and nearer, and, as it approaches the 
positive prime conductor a star of light will appear on 
the point, even at a distance of several inches, and this 
star of light will remain without much alteration until 
the point is brought up almost in contact with the knob ; 
then small sparks pass. If approached to the negative 
prime conductor in the same way, the discharge takes the 
form of a visible brush of non-luminous noiseless sparks 
when the point is still at a distance of two or three inches 
from the knob. It is easy to recognise these differences 
in the discharge to the point, and from them to know 
which prime conductor is positive and which is negative. 



STATIC BATH 203 

Static electricity means, literally, electricity " at 
rest." It is, however, only at rest when it is on the prime 
conductor and not leaking off. When it is applied to the 
body it flows on to and off from the latter. The body 
is alternately charged and discharged in some of the 
applications, so that static electricity becomes " current 
electricity." The current, however, is extremely small, 
not greater than a fraction of a milliampere, although 
its voltage is exceedingly high, reaching half-a-million or 
more. 

The Methods of Applying Static Electricity to the 
Patient. — ^The Static Bath. — In this method of applica- 
tion the patient is merely charged with electricity. He 
sits on a chair on the insulated platform. The chair 
should contain no metal. The patient is connected to 
the positive prime conductor of the machine by means of 
the metal rod with the crook at the end. The end is 
hooked over the sliding rod of the positive conductor, 
while the other end is placed on the floor of the insulated 
platform, not in contact with the patient or the chair. 
The patient and the insulating stool should be at least 
two feet away from the machine or from the walls and 
other objects. Before connecting the platform with the 
machine, the latter should be set in action and the polarity 
tested. The sliding rods are then placed in contact, and 
the platform is connected to the positive prime con- 
ductor. The sliding rods are then drawn as far apart as 
possible. The patient is charged positively, and when 
the voltage of this charge reaches a sufficient height the 
electricity leaks off from the surface of the body. The 
sensation is agreeable, and the skin feels as if it were in 
contact with cobwebs. For a stronger effect, or if the 
machine is not powerful, the end of the crook should be 
placed on a sheet of metal on the platform and two of 
the legs of the chair should rest on it. For a still stronger 



204 ESSENTIALS OF MEDICAL ELECTRICITY 

effect, the feet of the patient should rest on the metal 
plate. When the patient actually holds the metal rod 
the effect is strongest of all. The latter method of con- 



9i 


1 










i 





Fig. 57. — Stati„ Breeze 

nection between prime conductor and patient is to be 
adopted when powerful machines are not available 

(Fig. 57)- 
Treatment may be continued for fifteen minutes or 



STATIC WAVE CURRENT 205 

longer. It is the mildest form of static electrical treat- 
ment and it produces no unpleasant sensations. It is 
indicated for hypersensitive, nervous patients for the 
production of tonic effects. 

Its beneficial effects are possibly due to gentle stimula- 
tion of the sensory nerves of the skin, caused by the con- 
tinuous leakage of the charge from the surface of the 
body. 

Another method of giving the static bath is to charge 
the patient positively as before, and then bring the 
negative sliding rod gradually nearer to the positive 
till a spark passes ; at this moment the patient is dis- 
charged, but is quickly recharged and again discharged, 
and so on. A stream of sparks passes between the balls 
on the end of the sliding rods. The rate at which the 
sparks follow each other depends upon the width of the 
spark-gap and the rate at which the electricity is gener- 
ated. The width of the gap should be adjusted so that 
the sparks pass apparently continuously. The patient 
should be arranged on the chair on the platform with the 
feet on the metal plate, the latter connected by the brass 
rod with the positive prime conductor. If there is a 
sensation of sparks on the feet the boots should be 
removed. 

This modified method is rather more vigorous than 
that of simple charging. It is known as the method of 
" potential alternation " or " interrupted electrifica- 
tion." The sparks cause a continuous noise that is 
disagreeable to some patients. 

The Static Wave Current. — ^This is known also as the 
" Morton wave current." To apply it, the patient sits 
on a chair on the insulating platform . An electrode made 
of pliable sheet metal cut to the desired shape is applied 
to the part requiring treatment and connected to the 
positive prime conductor of the machine by means of a 



2o6 ESSENTIALS OF MEDICAL ELECTRICITY 



wire. The negative prime conductor is earthed by means 
of a brass chain connected to a water or gas pipe or 
radiator, or to a wood en or stone floor. The arrangement 
is shown diagrammatically in Fig. 58. The machine 
is started and the negative sHding rod is gradually 
separated from the positive. Sparks at once bridge the 
gap. With each spark there is a contraction of the 



Sjxirk ga|> 




<SK 



- Conncttpd. to 
Etettrode on (xtTtVnt 



Cha' rr I^OT Isatient 



CoTnnjpxtied 
to Eojrtk 



U 



iTiiulaTed Platforrr 



1] 



^ 



Fig. 58. — Arrangement of Apparatus for application of Static 
Wave Current 

muscles of the part under the electrode. If the sparks 
follow each other with sufficient rapidity the muscles are 
tetanised. If the shding rods are further separated the 
sparks pass with less rapidity, but the contractions be- 
come stronger. It is therefore advisable to have some 
device whereby the frequency of the sparks may be 
regulated. To some static machines is fitted a device 
called the " Baker field regulator." It is fitted to the 
Baker paper-disc machine and controls the frequency of 
the sparking. Such control is necessary for the successful 



REGULATION OF SPARK RATE 207 

application of the static wave current. The gap should 
be widened till the contraction with each spark is as 
strong as can be comfortably borne. The field regulator 
is then adjusted so as to give about three sparks per 
second. 

If there is no field regulator attached to the machine 
the frequency of the sparks may be lowered by placing 
a chair close to the insulated platform adjusting the 
distance till the frequency of the sparking reaches the 
desired rate. Another way is for the operator to bring 
an earthed single-point electrode to a suitable distance 
from the platform. 

The electrode that is applied to the patient may be 
made of thin pliable sheet metal, such as lead. It can be 
cut to the shape and size required and applied to the skin 
of the part requiring treatment. It should make good, 
even contact, and if the skin is dry it should be moistened 
with soap and water. The static wave current can be 
appUed to the rectum, uterus and prostate. Special 
electrodes have been designed for these parts. They are 
made of metal bulbs with hard rubber insulating handles. 
The bulb is passed into the rectum and the rubber handle 
remains outside and held by the patient in the correct 
position. If the uterus is to be treated, the electrode 
should be held so that the metal bulb is in apposition 
with it through the rectal wall. If the prostate is to be 
treated, the metal bulb is hollowed out partially, so as to 
make a better apposition with the gland through the 
rectal wall. 

When the patient is connected to the machine in the 
way described for the application of the static wave 
current, the body is charged positively — the electricity 
passing on to the body by way of the electrode. At the 
same time, the negative charge from the other prime 
conductor passes to earth. When the difference of 
potential between the latter charge and that on the body 



2o8 ESSENTIALS OF MEDICAL ELECTRICITY 

reaches a sufficiently high value, the resistance of the 
air space at the spark gap is overcome, the two charges 
neutralise each other, a spark passes across the gap and 
the body is suddenly discharged. The electricity leaves 
the body by way of the electrode. The body is alter- 
nately charged and discharged, the discharge being 
sudden and brisk and the charge relatively slow. Each 
time that the discharge takes place the muscles under 
the electrode give a sudden twitch. The current is 
therefore a to-and-fro surging of electricity to and from 
the body by way of the electrode. 

The static wave current has been recommended for a 
large number of maladies in which the morbid condition 
is inflammation with congestion and exudation. Good 
results have been claimed in cases of sprained joints, 
inflammatory swelling of the prostate, dysmenorrhoea 
with congestion of the uterus, and in diseases of other 
parts in which there is the same pathological condition. 

The mode of action of the static wave current is 
most probably mechanical, the sudden forcible rhythmic 
muscular contractions aiding the local circulation and 
removing inflammatory products. 

The Static Breeze (Static Brush). — If when the patient 
is charged from one conductor the single or multiple 
point electrode is connected to the opposite pole and 
brought near to him, the electricity passes between the 
points and the body. There are no sparks like those that 
pass between the prime conductors, but a cone of non- 
luminous blue-violet light bridges the gap between the 
points of the electrode and the skin of the patient. There 
is a faint blowing sound and the patient is conscious of a 
cool breeze blowing upon him ; hence the name " static 
breeze." 

To apply the static breeze, the patient is arranged as 
for simple charging and connected to the positive prime 



STATIC BREEZE 



209 



conductor. The single or multiple point electrode and 
the negative prime conductor are connected to earth 
(Fig. 59). The electrode is grasped by the operator and 
the points are directed towards the part of the patient 
requiring treatment. As it approaches closer the sensation 
perceived by the patient loses its cool character, and when 
the electrode is still closer there is the feeling as of a fine 




Fig. 59. — Arrangement of Apparatus for application of Static Breeze 

spray of hot water. If the electrode is placed very near 
the skin, sparks may pass and cause pain. If the brush 
is directed on to one spot of the skin without changing 
its position, a blister may be produced. For applying 
the breeze to the scalp, a light crown-shaped metal elec- 
trode is often used. It is suspended above the patient's 
head, either from an insulated pole or from a rod pivoted 
to the case of the machine. It is connected to the 
negative prime conductor. 

If the skin is covered by a dry cloth or by the ordinary 
o 



210 ESSENTIALS OF MEDICAL ELECTRICITY 

clothing, the breeze produces a stiU hotter sensation, 
which may be painful. The skin should not be damp 
with sweat, otherwise the breeze wiU lose some of its 
effect. If necessary, the skin may be bared and then 
covered by a shawl, upon which the breeze may be 
directed. 

It is thus possible, by means of the static breeze, 
to produce any degree of cutaneous stimulation, sHght, 
with agreeable sensations, to a burning, tingling sensa- 
tion causing pain. The stimulation of the peripheral 
sensory nerves causes a reflex rise of blood pressure, and it 
is to this that the good effect following treatment by the 
static breeze is chiefly due when applied for general 
effects. Patients whose pressure is raised are not likely 
to benefit from the static breeze. Those whose sjmaptoms 
(e.g. headache) are the result of a low pressure are greatly 
benefited and headache will often disappear during the 
application. The breeze, applied locally, has often a 
healing effect on chronic ulcers, bringing about hyper- 
semia and, possibly, disinfection by means of the ozone 
and oxides of nitrogen produced. In other skin affec- 
tions, such as pruritus, eczema and psoriasis, it often 
produces good results. 

Static electrical applications, especially when the 
breeze is appHed to the lumbar and sacral region, have 
a beneficial influence in cases of menstrual irregularity 
and amenorrhaa. 

Electrical Sparks. — If the point electrode is replaced 
by the ball electrode the discharge between the patient 
and the latter does not take place in the form of a brush, 
but of noisy sparks. The sensation is not pleasant and 
resembles that of a sudden blow. To administer sparks, 
the patient is arranged again as for simple charging and 
the ball electrode connected to earth is brought close 
enough to allow the discharge to take place. As the 



STATIC SPARKS 211 

sparks produce an unpleasant sensation it is best to 
manipulate the electrode so as to allow only one spark 
at a time to pass. This is done by making the electrode 
describe a curve past the place on which it is desired 
that the spark should be directed, and if the manipula- 
tion is skilful and rapid the electrode is out of range 
before a second spark can pass. 

The length of spark administered should vary accord- 
ing to the part to be treated, longer sparks, ten inches or 
more, for larger parts, such as the hip or thigh, and 
shorter sparks down to half-an-inch for smaller regions, 
such as the wrist or finger. The length may be diminished 
by slowing the rate of revolution of the plates and by 
using small-size ball electrodes ; and the length can be 
further diminished if the operator places his foot close 
to the insulating stool. The patient should always be 
warned before the passage of a spark. 

Treatment by means of static sparks is of value in 
some cases of Ixmibago and pain in the muscles, some- 
times relieving the pain instantaneously. Probably the 
muscular wrench removes deep-seated congestion and 
breaks down adhesions. 

A modification of the sparking method consists in the 
use of a roller in place of the knob. It is rolled, over the 
clothed surfaces of the skin and a shower of stinging 
sparks passes to the patient. The thicker the layer of 
clothing the more intense the effect. In employing this 
method the operator should first place one foot on the 
platform before placing the roller in position, and also 
before removing it. In spark applications it is a good 
rule to always warn the patient of what is coming. 
Sparks from the roller cause intense sensory stimulation, 
with muscular contraction. 

Short static sparks are useful for the discovery of 
tender points in the region of joints and along the course 
of nerves. Where the patient complains of general pain 



ai2 ESSENTIALS OF MEDICAL ELECTRICITY 

all over, an administration of sparks will reveal the 
presence of tender spots ; to these spots subsequent 
treatment may be specially directed. 

The Static Induced Current. — ^This current must not 
be confused with the static wave current. Two Leyden 
jars are introduced into the circuit, in series with the 

S|>ark G<M) 

-oa 




Fig. 6o. — Arrangement of Apparatus for application 
of Static Induced Current 

patient (Fig 60). The inner coats are connected one 
with each prime conductor. The outer coats are con- 
nected by a wire. If the machine is now started and the 
sliding rods drawn a short distance apart, sparks will 
bridge the gap. If now a gap is introduced in the circuit 
joining the outer coats of the jars, sparks will bridge this 
gap also in synchronism with the others. If the patient 
is included in this circuit he wiU experience strong 
muscular contractions, with little or no pain. To apply 
this current to the patient the insulating platform is 
not required. Two electrodes are needed, of the same 
kind as those used for the static wave current. They 
are appHed to the body, the sHding rods are placed in 
contact and the machine is started. The sliding rods 
are cautiously drawn apart till the muscular contraction 
is as strong as the patient can bear. 
Ths static induced current has been appHed with 



STATIC INDUCED CURRENT 213 

success to cases of obstinate constipation. One electrode 
is introduced per rectum (an electrode like that used with 
the stat:ic wave current may be employed). The other, 
a plain metal sheet, is placed on the abdominal wall. 
The current is started and its strength increased as far 
as the patient can tolerate. 

When static treatment is being administered in the 
ways described and the operator has not a machine of 
sufficient power, better results can be obtained by attach- 
ing two small Leyden jars to the prime conductors in the 
way described for the static induced current, the outer 
coats are connected, one to the insulating platform, the 
other to the electrode. 



CHAPTER XIV 

INDEX OF ELECTRICAL TREATMENT 

In the following pages are considered the maladies and 
morbid conditions for which electrical treatment may be 
applied. If the best results are to be obtained the general 
treatment should not be brought to a close when the 
electrical treatment is instituted, especially in those 
maladies in which electricity is applied in order to treat 
one or more symptoms of the general disease. In local 
conditions, too, better results are frequently obtained by 
combining the electrical treatment with the local treat- 
ment previously prescribed. 

Acne Vulgaris. — ^Electrical treatment is sometimes 
successful in cases of acne vulgaris that have proved 
refractory to other methods. High-frequency treat- 
ment should be applied, using a vacuum electrode and 
moving it over the affected area. An er3^hema is 
produced and the ozone and nitrous and nitric acids 
formed possibly have some disinfectant action on the 
infected sebaceous glands. The treatment should be 
repeated twice or thrice weekly and each session should 
last about fifteen minutes. Diathermy may be tried, 
also using the vacuum electrode. The latter is kept in 
contact with the skin and moved about over the surface. 
It is connected to one pole of the diathermy machine, 
while the other is connected to a metal handle electrode 
grasped by the patient. 

lonisation with sahcyHc ions has been recommended, 
its action being probably a disinfection of the sebaceous 
glands 

214 



ANEURYSM 215 

Acroparaesthesia. — ^This may be treated by applica- 
tion of rhythmically varying sinusoidal or faradic cur- 
rents in an arm bath. Slow improvement commonly 
results. 

Alopecia Areata. — ^Electrical treatment for this con- 
dition is sometimes required. lonisation with copper or 
zinc should be tried first. A week later high-frequency 
spark discharges from a vacuum electrode should be 
administered. 

Amenorrhoea. — ^The static breeze is very effective 
in restoring regularity of menstruation in cases of 
amenorrhoea and irregularity due to general debility. 
It is necessary, before applying this treatment, to exclude 
disease of the pelvic organs as a possible cause of the 
amenorrhoea. The patient is placed on the insulating 
platform and charged positively, while the negative 
breeze is directed against the spine and lumbar region. 
The treatment should be repeated daily or every other 
day. 

Anal Fissure. — Zinc ionisation is an excellent treatment 
for this. A zinc rod wrapped in wool soaked in zinc 
sulphate solution is placed in the fissure and a current of 
15 milliamperes is passed for twelve minutes. After a 
week the fissure heals or becomes much smaller. A 
second application may be made, if, at the end of the 
second week, the fissure has not healed. 

Aneurysm. — ^Electrical treatment of aneurysms has 
been reserved for those for which surgical methods were 
without avail, but at the present time it seems to be rarely 
employed. The usual plan adopted was to insert two 
needles through the wall of the sac and pass a constant 
current between them. Coagulation would then take 
place around the needles as a result of the formation of 
acids and alkalies. This method of treatment has not 



2i6 ESSENTIALS OF MEDICAL ELECTRICITY 

succeeded in bringing about anything more than tem- 
porary delay in the expansion of the sac. Puncture 
of the sac is not unattended by danger from haemorrhage. 

Aphonia. — ^Hysterical aphonia may be treated by 
applying the faradic current to the larynx. An active 
electrode provided with a closing key and carrying a 
chamois-leather-covered button is apphed to the front 
of the neck over the larynx. The indifferent electrode 
is placed on the back of the neck. The current is 
passed for short periods with intermittent periods of 
rest. 

Another method of treatment is to apply the static 
wave current to the front of the neck. Or static sparks 
may be administered to the same region. 

Arthritis. — (i) Injuries to Joints — Sprains. — Such cases 
respond well and quickly to treatment by the galvanic 
current. Electrodes of the type used for ionisation and 
described on page 77 should be used. They should be 
soaked in salt solution. One is applied to the joint so as 
to envelop it as completely as possible. It is connected to 
the negative pole of the source of current. The other 
is applied to some other part of the limb. If there is much 
pain and tenderness, the electrode around the joint may 
be soaked, not in salt solution, but in sodium saUcylate. 
Salicylic ions will then migrate through the skin and 
diminish the pain. The treatment should be given daily 
in the acute cases, twenty minutes each session. Chronic 
cases may receive the treatment on alternate days. 

Joints that are stiffened by fibrous adhesions resulting 
from past injury can be rendered mobile by ionisation 
with the chlorine ion. The process is slow, but the treat- 
ment is effective. It should be applied in the way just 
described and repeated twice or thrice weekly. 

Similar results can be obtained if the adhesions are due 



JOINT AFFECTIONS 217 

to old inflammation, provided that the cause responsible 
for the inflammation is no longer present. 

(2) Gouty Arthritis. — Cases of acute gouty arthritis 
do not come under electrical treatment. For the chronic 
cases ionisation with salicylic ions produces good results. 
If more than one joint has to be treated, the electrode 
connected to the positive pole can be soaked in a 
solution of a lithiimi salt and applied to another joint. 
The lithium ions are not more effective than the salicylic. 

(3) Gonorrhoeal Arthritis. — Good results have been 
reported in the treatment of the acute form by salicylic 
ionisation. For the sub-acute and chronic cases the 
same treatment is of value. Diathermy seems to be a 
valuable method of treatment of gonorrhoeal arthritis ; 
this is in accordance with the writer's experience. The 
rise of temperature through the joint possibly acts as 
a depressant on the vitality of the gonococcus. The 
adhesions that are left in a joint after gonococcal infec- 
tion can be successfully treated by chlorine ions if the 
organism is extinct (see treatment of stiff joints under 
" Injuries to Joints "). 

(4) Rheumatoid Arthritis. — ^There is no known form 
of electrical treatment that is a cure for rheumatoid or 
osteo-arthritis. In the intervals between acute attacks 
some good may be done by ionising the joints with 
salicylic or iodine or lithium ions or by diathermy, but 
exacerbations are likely to occur, even during the course 
of treatment, if the cause responsible for the disease in 
any particular case (such, e.g., as a septic focus) is not 
discovered and removed. If this can be done, electrical 
treatment, diathermy or ionisation (with saUcyhc or 
chlorine ions) is of value in promoting the absorption of 
effusion and the resolution of scar tissue and return of 
mobility. 

Some cases of rheumatoid arthritis are benefited 
temporarily by the sinusoidal current, rhythmically 



2i8 ESSENTIALS OF MEDICAL ELECTRICITY 

varied in strength, applied in a Schnee bath or in a full- 
length bath. 

(5) Osteo- Arthritis (see under "Rheumatoid Arthritis"). 

Anterior Poliomyelitis {Infantile Palsy). — In this dis- 
ease there are, for treatment, the spinal cord, motor 
nerves, muscles and the other tissues of the limb, includ- 
ing the skin. In the affected region of the spinal cord 
there are, in the first place, anterior horn cells that have 
been actually destroyed by the disease. The motor 
fibres arising from them and the muscle fibres supplied 
will degenerate and will ultimately be replaced by fibrous 
tissue and no treatment has any effect upon them. In 
the second place, there are anterior horn cells that have 
been damaged to varying degrees but not destroyed. 
Many of these wiU recover under appropriate treatment, 
and the muscle fibres that have been put out of action 
will be kept, by suitable treatment, in a condition of good 
nutrition, during the period while the nerve cells and their 
axons are returning to their normal condition. In the 
third place, there are frequently undamaged muscle fibres 
among others that have been injured ; this is especially the 
case in the lower limb, where the muscles are supplied from 
anterior horn cells Ijdng at different levels in the cord. 
Electrical treatment will stimulate these and cause their 
hypertrophy. In the fourth place, there are the other 
tissues of the limbs that are impoverished from poor blood 
supply, that results if many muscles are out of action. 
The skin becomes cyanosed and chilblains and ulcers 
often develop. Suitably applied electrical treatment will 
benefit all these conditions by its power of producing 
general stimulation of the dormant tissues and improving 
their blood supply. The improvement is first seen in the 
skin. Cold blue skin that has not responded to other 
treatment, also chilblains and trophic ulcers, begin to 
disappear as soon as the electrical treatment is started. 



ANTERIOR POLIOMYELITIS, ETC. 219 

Electrical treatment is most effectively carried out 
by applying rhythmically varying sinusoidal current in 
baths. The details are described in Chapter IX., dealing 
with the treatment of paralysis. Under this treatment 
the blueness of the skin and the chilblains and ulcers 
rapidly disappear. The recovery of voluntary power in 
those muscles of which the motor cells and nerves have 
not been destroyed is a slower process, but good results 
will be obtained with perseverance, and the return of 
normal reactions to muscles which have shown RD, or 
have shown no response at all to electrical stimulation, is 
often observed. The best results of electrical treatment 
of infantile paralysis are seen in hospitals where the 
question of expense does not arise and cut short the treat- 
ment. At St Bartholomew's Hospital the mothers bring 
their children up regularly, month after month, and the 
good results that follow electrical treatment when pro- 
perly applied with patience and perseverance, are seen. 
When applied in baths, using the rhythmically varied 
sinusoidal current, the amount of attention required is 
reduced to a minimum. 

Asthma. — Static electrical treatment, in the form of 
simple charging, combined with the application of the 
roller electrode to the thorax, has produced good results 
in some cases. 

Boils. — SmaU boils can be effectively treated by 
ionisation with zinc, a pad saturated in zinc sulphate 
solution being applied. 

Carbuncles. — Leduc recommends their puncture to the 
base by a tenotome and the insertion into the channel of 
a zinc needle. This is connected to the positive pole of 
the source of current and a current of 30 milliamperes is 
applied for about thirty minutes. 

Carcinoma (see " Malignant Growths "). 



220 ESSENTIALS OF MEDICAL ELECTRICITY 

Cardiac Failure. — Incases of impending death, electrical 
stimulation of the heart itself should not be attempted, 
as it is just as likely to cause the very thing we wish to 
prevent — ^that is, stoppage of the heart's action. It is 
best to use an induction coil with a long fine secondary 
wire, and metallic brush electrode to stimulate the surface 
of the body. This sets up a strong reflex stimulation of 
the heart and diaphragm by way of the vaso-motor and 
respiratory centres. The nose and upper lip are good 
points from which to influence respiration. If desired, the 
phrenic nerves in the neck may be directly stimulated 
and so set up contractions of the diaphragm. Two 
electrodes, each about one inch in diameter, are to be 
used. They are mounted on handles, and one of them is 
provided with a closing key. They are applied under the 
posterior border of the stemo-mastoid muscles, and the 
circuit closed and opened at intervals of about two 
seconds. This has been successfully employed in 
chloroform poisoning. 

Chilblains. — ^These can be very effectively treated in 
arm baths or foot baths by the rhythmically varying 
sinusoidal current. For home treatment an induction coil 
may be used ; its handles are placed in separate bowls of 
warm water, in which the hands or feet are immersed, 
one in each bowl. Some rhythmic variation can be pro- 
duced by sliding the secondary over the primary or pulling 
the metal sleeve over the iron core. If the skin over the 
chilblain is not intact, it should be covered by a water- 
proof cloth, such as oiled silk or thin sheet rubber. 

Chorea. — Static electrical treatment was formerly 
appHed to this disease with excellent results. The child, 
supported by its mother on the insulating stool, is con- 
nected to one prime conductor. The other is connected 
to a ball electrode and sparks are directed along the spine 



CONSTIPATION 221 

of the patient and the affected hmbs. This method of 
treatment has fallen into disuse. 

Colitis. — lonisation with silver ions or with zinc ions 
has been recommended by Curtis Webb. As a result of 
this treatment the motions became natural in consistency 
and frequency, the mucus disappeared and the flatus 
diminished. (See page 85.) 

Congestion. — ^The good results that foUow the treat- 
ment of injuries in the region of joints, accompanied by 
sweUing and effusion of fluid (see under "Arthritis — 
Injuries to Joints "), illustrate the influence of the constant 
current on congestion. The current may well be apphed 
as an aid in the removal of inflammatory products after 
the agent responsible for the inflammation has been 
removed or has ceased to operate ; the current also aids 
the absorption of fluid exudations. Thus in cases of 
crutch palsy the treatment should include the appHca- 
tion of the constant current to the area in the region of 
the pressure, where there is likely to be congestion. 

Constipation. — ^When this is due to atony of the 
muscular coats of the intestine, electricity is probably 
the most efficient method of treatment known. Large 
currents and large electrodes are to be used. If the 
constant current is to be employed the anode is the 
indifferent electrode and it is placed under the lumbar 
spine as the patient reclines. The kathode or active 
electrode is a padded metal disc about four inches in 
diameter. It is soaked in saline and applied with firm 
pressure over the front abdominal wall, moving it round 
rather slowly from the caecum along the course of the 
colon to the sigmoid flexure, where it is allowed to rest 
from two to five minutes, when the process is repeated. 

This should be done every other day for three or four 
weeks. A sinusoidal current of low frequency — from one 



222 ESSENTIALS OF MEDICAL ELECTRICITY 

to two periods per second may be used if the constant 
current is ineffective. Or the constant current may be 
made to vary its strength rhythmically by including a 
rhythmic interrupter in the circuit. 

Such treatment is frequently followed by gradual im- 
provement and restoration of the normal frequency of 
defaecation that persists after the treatment is brought 
to a close. 

In obstinate cases one of the electrodes should be 
placed in the rectum, the other on the abdominal wall. 
The rectal electrode consists of a metal tube enclosed, 
except at one end, in a loose membrane bag. This metal 
tube serves to conduct the current, and at the same time 
allow the introduction of saline into the membrane bag 
when the latter is placed in the rectum and so distend it 
that its walls come in contact with the rectal wall. The 
rhythmically interrupted or slow sinusoidal current is used 
for about ten minutes. It sometimes happens that the 
bowel is provoked to action before this time elapses. 
In all cases the ordinary rules for dealing with constipa- 
tion must not be neglected — such as exercise, massage, 
suitable diet and use of laxatives until the case so far 
improves that the latter can be gradually reduced to 
vanishing-point . 

The static wave current and static induced current 
should be tried in cases that resist other methods of 
treatment. (See pages 205-207 and 212.) 

Corns. — ^The opinion has been expressed by Lewis 
Jones that painful corns are the result of an infection 
of an ordinary callosity by some micro-organism, the 
caUosity being, when not infected, painless. The treat- 
ment recommended is ionisation with zinc. It is neces- 
sary, however, to make some preliminary preparation of 
the corn before the ionisation. The tough, thickened 
skin is dry and will not conduct a current. A compress 



CORNS 223 

soaked in 1% zinc sulphate should be worn in contact 
with the corn for twelve hours beforehand. The thick 
skin will then be moistened and some ions will diffuse 
in and conduct the current. One application is often 
enough. 

The patients will not always carry out the instructions 
to keep a moist compress in contact with the corn, and 
they sometimes arrive for treatment with the corn dry. 
If, then, an attempt is made to ionise it, no current will 
flow unless part of the pad comes in contact with the 
surrounding skin, in which case, all the current will pass 
in that way and no ions will penetrate the corn. 

An alternative method is to apply salicylic acid and 
collodion for a few days beforehand and then ionise with 
salicylic ions after the thick skin has separated. 

Another method, which the author has used with 
success in some cases where the corn is very thick and 
hard, is to cut away as much as possible of the epithelium 
and ionise with a solution of potassium iodide (1%), 
containing in solution iodine (1%). A wall is formed 
around the corn of some material, such as plasticine 
or modelling wax, for the purpose of holding the 
solution and preventing the entry of the current in 
any way other than through the corn. The chamber 
thus formed is filled with the solution. The conducting 
cord (from the negative pole) is fixed near it, say by a 
safety pin through the rubber tube covering and the 
cushion on which the foot lies. A fine flexible copper 
wire is wound round the bare metal end of the conducting 
cord. The free end of the flexible wire is laid across the 
top of the plasticine chamber and embedded in its wall, so 
as to make contact with the fluid inside. Good cotitact 
between the other end of the flexible wire and the con- 
ducting cord is secured by partly turning back the rubber 
covering of the latter and then replacing it over the 
flexible copper wire and so keeping the metal surfaces 



224 ESSENTIALS OF MEDICAL ELECTRICITY 

in contact. The solution in the plasticine chamber may- 
be held in place without fear of it running out by filling 
the latter with cotton wool before adding the fluid. 

Corneal Ulcers. — Zinc ionisation is often successful in 
the treatment of " Mooren's ulcer." A tuft of cotton 
wool soaked in a i% solution of zinc sulphate is 
wound round the end of a zinc rod, with its end 
free. The rod is connected to the conducting wire 
leading to the positive pole of the battery, and the 
free end of the tuft is placed on the ulcer, moving it 
sUghtly so as to come in contact with all parts of it. 
A current of i to ij milUamperes should be passed for 
four or five minutes. Cocaine should be applied to the 
eye before the treatment. 

Corneal Opacities. — Considerable improvement in 
vision follows ionisation with chlorine ions. The 
lachrymal secretion contains sodium chloride in solution 
(and, therefore, chlorine ions), so if the lid is closed and 
the electrode, in the form of a lint pad soaked in salt 
solution, placed on the exterior and made the kathode, 
the passage of a current will cause the migration of the 
chlorine ions into the cornea. No anaesthetic is required. 
A current of 5 milliamperes may be borne, for two to four 
minutes. 

Disorders of Digestion. — ^Electricity is useful in some 
disorders of the digestive tract. A slow sinusoidal 
current is most useful, one electrode being placed on the 
lower dorsal spine and the other over the epigastrium. 
It should be applied daily or at least thres times a week 
for ten minutes. Dilatation of the stomach caused by 
atony of the wall has been successfully treated by this 
means. 

Disseminated Sclerosis. — ^Electrical treatment is some- 
times requested for this disease. It cannot be said that 



EPISCLERITIS 225 

any form of electrical treatment is of value. Temporary 
improvement, which is occasionally noticed, is not likely 
due to any form of treatment that the patient is happen- 
ing to have at the time, as such improvement often occurs 
even when no treatment is given. 

Dupuytren's Contraction. — Occasionally, though not 
as a rule, good results are obtained in the treatment of 
this condition of the palmar fascia by chlorine ions. 
Treatment should be continued for a month or six weeks 
before it can be seen whether any improvement is likely 
to take place. 

Dysmenorrhoea. — Many cases of this condition are 
reUeved by static electrical treatment. The patient is 
charged positively and the negative breeze is applied to 
the spine and loins. Lewis Jones recommends that the 
treatment should be given daily for a week or two before 
the onset of the period. With the commencement of the 
flow it should be left off and afterwards reapplied as 
before, prior to the onset of the next period. 

Endometritis. — Sloan and other writers have obtained 
excellent results in the treatment of septic endometritis 
by zinc ionisation. A zinc sound is introduced into the 
uterus and connected to the positive pole of the source 
of current ; a current of 20 to 40 milliamperes is passed 
for fifteen minutes. If there is difficulty in withdrawing 
the sound at the end of the operation, the current, after 
reaching zero, should be reversed and allowed to flow 
in the opposite direction for a few minutes. Discharge 
follows for some days after the treatment and vaginal 
douches should be given. If it does not disappear after 
ten days the ionisation should be repeated. 

Episcleritis. — This may be treated by ionisation with 
salicyhc ions. A pad soaked in the solution of sodium 
salicylate is placed on the external aspect of the hd and 



2^6 ESSENTIALS OF MEDICAL ELECTRICITY 

a current as strong as can be comfortably borne (5 to 10 
milliamperes) is passed for ten minutes. 

Exophthalmic Goitre. — Cardew recommended the use 
of the constant current passed through the thyroid gland 
from the lower cervical spine to the side of the neck. 
Currents from 2 to 3 milliamperes, for six minutes, to be 
appUed three times daily. 

Fibrositis. — lonisation with iodine or salicyhc ions is 
sometimes effective in relieving the pain associated with 
this condition. 

Fissure (see Anal Fissure). 

Fistula. — Some cases of rectal fistula successfully 
treated by zinc ions have been reported. Billinkin's 
method was to pass a zinc rod — its tip insulated by a cap 
of wax — ^into the fistula until the insulated end reached 
the inner end of the fistula. A current of 6 milUamperes 
was passed for three minutes. The process was repeated 
every two or three days, the zinc rod passed less far up 
the fistula each time. The fistula began to heal first at 
its upper end, and the healing process extended down- 
wards tiU the whole length had healed. 

Furuncle (see Boil). 

Gouty Arthritis (see Arthritis — Gout). 

Gonorrhoea. — Gonococcal urethritis has been success- 
fully treated by ionisation with zinc or copper. W. J. 
Morton's method was to pass a sound with a brass stem, 
insulated, except at its free bulbous extremity, along the 
urethra up to the neck of the bladder. The current was 
then turned on and the stem was then slowly extracted, 
so that the ions from the bulbous end could pass into 
the waU of the urethra throughout its length. To one 
patient treated in this way one application only was 



HEMIPLEGIA 227 

given, and he remained free from infection for a year, 
when he then acquired it again. 

Fenwick successfully treated two cases of long- 
standing chronic urethritis by zinc ions. A zinc rod 
was covered with lint and soaked in 2% zinc sulphate 
solution. It was inserted into the previously cleansed 
urethra, through a cannula, which was afterwards with- 
drawn. Small currents were used, 2 to 5 milliamperes. 

Haemorrhoids (see Piles). 

Headache. — ^Headache that is associated with low 
blood pressure is best treated by the static breeze applied 
to the scalp, the body being positively charged. The 
pain often disappears during the first treatment, a result, 
most probably, of the rise of blood pressure. Headache 
associated with high blood pressure may be treated 
by general diathermy, the endeavour being to lower 
the pressure. For the description of the method of 
application see under High Blood Pressure. 

Hemiplegia. — Cases of paralysis that are due to 
lesions of the upper motor neuron will benefit if the cause 
responsible has disappeared or is no longer active. If, 
however, there is late rigidity, much cannot be expected 
from electric treatment. The treatment is suitable for 
cases of hemiplegia due to cerebral haemorrhage. It 
should begin a fortnight or three weeks after the haemor- 
rhage and be continued, three times Wc;ekly, for a month. 
If improvement occurs the treatment may be continued 
for further periods of one month each, tiU no further 
benefit is noticed. The treatment is best given in a full- 
length bath (rhythmic sinusoidal current) if the lower 
hmbs are affected. The Schnee bath may be used when 
no full-length bath is available, and it can be used when 
the paralysis affects either the lower or the upper limbs. 

Leduc recommends that treatment should be given to 



Z28 ESSENTIALS OF MEDICAL ELECTRICITY 

the lesion when present in the brain, by passing the 
constant current through it from the back of the neck 
(anode) to the forehead (kathode). The treatment should 
be given daily, or on alternate days, and for fifteen 
miQutes, with a current of 20 milliamperes. 

High Blood Pressure. — Some writers have obtained a 
lowering of high blood pressure by means of general 
applications of high frequency, given on the auto-con- 
densation couch ; others have been unsuccessful, although 
the same method was used. Possibly the condition of the 
arteries, whether in an advanced state of sclerosis, or in 
the pre-sclerotic condition, may be the factor which 
determines the effect of high-frequency applications. 

To carry out the treatment the patient should be on 
the auto-condensation couch and the current appHed 
daily for about a week or ten days. The blood pressure 
should be measured after each treatment, and if it sinks 
during an application a watch should be kept for 
symptoms of syncope, and if there is a feeling of faint- 
ness the treatment should be stopped, and resumed the 
following day. 

Nagelschmidt speaks highly of diathermy as a means 
of lowering high blood pressure. One electrode is 
placed on the precordium, the other on the back of the 
chest. Applications not longer than five minutes at the 
commencement. They may be lengthened later. The 
blood pressure should be estimated before and after each 
treatment. 

Hypertrichosis. — Superfluous hairs may be removed 
by means of the electrical current. It has been mentioned 
that the passage of the constant current through the 
tissues is accompanied by the formation of caustic soda 
and hydrogen at the kathode. If the kathode is a fine 
platinum wire and is introduced into the hair follicle the 
caustic soda will destroy the foUicle and the hair can be 



INCONTINENCE 229 

lifted out. The operation causes a stinging pain, but 
not greater than the patient can bear. 

A local anaesthetic should not be applied. The details 
of the operation are described on page 89. After each 
hair is removed a small zone of hyperaemia is left round 
each follicle and sometimes oedema. These soon dis- 
appear, and if the operation is neatly done, with a small 
current (not more than 2 milliamperes) and short appli- 
cations, no scar will remain. If a group of hairs in close 
proximity is removed at one sitting it is likely that a scar 
will be left. A small proportion of hairs will return, 
because it is not possible to ensure entire destruction of 
the foUicle without strong currents. The hairs that 
return can always be treated again when they reach a 
sufficient size. 

The operator must always warn the patient of the 
likeUhood of the return of a small number of hairs. 

Hysteria. — The most useful role of electricity in 
hysteria is for the removal of paralysis, anaesthesia and 
spasm (Lewis Jones). The current from the induction 
coil, applied by the ordinary moistened electrodes, or by 
the wire brush, may be used. Sparks from a static 
machine are effective and have an additional psychic 
effect. For the general hysterical condition, apart from 
local symptoms, the long bath with sinusoidal currents, 
or the static breeze, may be used. 

Incontinence of Urine. — The cases of incontinence of 
urine for which electrical treatment may be given with 
prospect of success are those due to weakness of the 
sphincter, and those in which the incontinence is really 
an unconscious act of micturition occurring during sleep. 
Incontinence resulting from weakness of the sphincter 
occurs in female patients and does well under electrical 
treatment. The rhythmically varying faradic current 
is used. One electrode is a metal sound. It is placed in 



230 ESSENTIALS OF MEDICAL ELECTRICITY 

the urethra without passing into the bladder. The other 
electrode is a padded metal plate and is placed on the 
spine in the lower dorsal region so as to overUe the 
lumbar enlargement of the spinal cord. Treatment may- 
be given daily for periods of ten or fifteen minutes and 
less frequently as improvement proceeds. 

For cases of nocturnal micturition during sleep the 
same treatment may be given when the patient is a 
female. In male patients one electrode is placed on the 
lower dorsal spine, the other on the perinaeum, A 
special electrode is used for applying to the perinaeum 
(Fig 6i). It is composed of a wooden handle bearing 

Metal end covered with chamois leather 




) 



Vulcanite ring 
Fig. 6i. — Electrode for Enuresis (seen in section) 

a cone-shaped metal end-piece with rounded apex. The 
latter is covered by chamois leather secured in position 
by a vulcanite ring which slides over the cone and fits 
tightly around its base. Stroking movements of the 
leather-covered end of the electrode are made over the 
perinaeum and so produce the rhythmic variation. For 
cases of nocturnal micturition during sleep stronger 
applications are necessary, so as to produce a strong 
sensory impression on the urethra, and so on the cerebral 
sensory centres. In this way the patient is made more 
strongly aware of the condition of the urethra, so that 
when the bladder is about to expel its contents into this 
channel the cerebral centres receive stronger impressions 
and the patient is awakened. Lewis Jones recommended 
the appUcation of the galvanic current after the faradic 



LACHRYMAL OBSTRUCTION 231 

for three or four minutes, with reversals of direction 
every five seconds, and of a strength of 5 to 10 milli- 
amperes. 

Cases of incontinence that are due to irritability of the 
bladder wall do not benefit under electrical treatment. 
The irritability is due to inflammation of the bladder wall 
and the incontinence will persist until the cystitis is 
removed. 

Ingrowing Eyelashes. — ^These can be removed by 
electrolysis (see under Hypertrichosis), but the opera- 
tion is painful, on account of the sensitiveness of the part. 
Many of the hairs are fine and difficult to remove. 

Insomnia. — ^Electrical treatment is occasionally given 
for insomnia, in conjunction with other methods of 
treatment. Patients whose blood pressure is low are 
best treated by the static breeze ; those in whom it is 
high should receive g/eneral high frequency or general 
diathermy. 

Intermittent Claudication. — ^Electrical treatment in a 
Schnee bath, with rhythmically and slowly varying 
faradic or galvanic currents, may be applied in these 
cases. Good results are obtained, but courses of treat- 
ment should be repeated periodically. 

Joints, Injuries and Diseases (see under Arthritis). 

Keratitis. — ^Traquair recommends the use of zinc ions 
for the treatment of purulent keratitis and has obtained 
good results by this method. He devised a special 
electrode for the purpose. It consists of a zinc rod with 
a celluloid cap at its end. The cap is filled with cotton 
wool soaked in J% zinc sulphate solution. The wool is 
brought into contact with the ulcer and stroked over it. 

Lachrymal Obstruction. — Obstruction of the canaliculi 
can be removed by inserting a platinum probe into the 



232 ESSENTIALS OF MEDICAL ELECTRICITY 

canaliculus ; an indifferent electrode is placed in some 
convenient situation ; a constant current, 2 to 4 milli- 
amperes, is passed from the indifferent electrode to the 
platinum probe for thirty seconds. The probe is there- 
fore the kathode. Two or three sittings are required. 
The obstruction is permanently removed (Jessop and 
Steavenson). 

Locomotor Ataxy. — Some of the symptoms of this dis- 
ease can be relieved by the application of the constant 
current to the spine. One electrode (the anode) is 
applied to the cervical spine, the other to the lumbar 
spine. The pains and unsteadiness of the gait are 
relieved in many cases. The same treatment is recom- 
mended for the crises — agastric, laryngeal and vesical. It 
is said that if it is applied during a crisis the pain is 
relieved in a few minutes. 

Lupus Vulgaris. — Of the electrical methods of treat- 
ment of lupus vulgaris two may be mentioned : 
(i) lonisation with zinc ions. This method gives good 
results in cases where nodules persist after healing of 
ulceration by Finsen light or X-rays. The method 
recommended by Taylor and MacKenna is to first rub 
the part with liquor potassae. This denudes the nodules 
of their epithelium. The liquor potassse is washed away 
with water and the part of the skin containing the 
nodules is covered with a lint pad saturated with 2% 
zinc chloride solution, or 10% zinc sulphate. The 
current is passed for ten to thirty minutes. The 
ionised part gradually becomes swollen and red, and a 
crust forms on the surface. A fortnight after the ionisa- 
tion the crust drops off and the nodules are then seen 
to have become smaller. Some may have disappeared. 
So long as any nodules remain the treatment is re- 
peated fortnightly. A smooth elastic scar results. 
(2) " Reyn's electrolysis." The patient takes, by mouth, 



MALIGNANT GROWTHS 233 

a large dose (40 to 60 gr.) of potassium iodide. An hour 
later the lupus nodules are transfixed with a group of 
platinum or iridium needles set close together on a suitable 
handle. A current of 3 to 4 milliamperes is passed from 
the needles (the anode) through the nodule and to an in- 
different electrode for three minutes. The needles are then 
taken out and reinserted in a different position and the 
current again passed for a similar time. The process is re- 
peated till the nodule has been transfixed in all directions. 
Iodine is set free around the needles and destroys bacilli 
in the neighbourhood. The following events occur 
during the process. The potassium iodide is absorbed 
and passes into the tissue fluids. The latter, therefore, 
contain iodine ions. Those present in the lupus nodule 
are attracted to the needles (which form the anode). 
They give up their electric charge and then become free 
iodine. 

The treatment is repeated daily until the nodule has 
disappeared. 

No necrosis of the tissue takes place. 

This method of treatment is suitable for lupus of the 
mucous membranes. 

Malignant Growths. — Malignant tissue can be de- 
stroyed by means of zinc ions, using very strong currents 
and long applications, under general anaesthesia. Several 
apphcations are necessary. Betton Massey is the advocate 
of this method. It is described on page 97. Keating- 
Hart uses the sparks from powerful high-frequency 
apparatus. " Fulguration " is the name given to this 
form of treatment. The destruction caused by " fulgura- 
tion " is most probably due to heat. 

The most successful method of treatment of inoperable 
growths is by diathermy. For particulars see page 190. 

Menstrual Irregularities (see Amenorrhoea and 
Dysmenorrhcea). 



234 ESSENTIALS OF MEDICAL ELECTRICITY 

Mental Diseases. — ^The cases most likely to benefit are 
those of melancholia in adolescents and mental apathy. 
These are often accompanied by failure of general nutri- 
tion. In the cases reported the method employed was a 
course of sinusoidal baths, and the results were so good 
that it should be always tried. The general effects were 
a complete, or nearly complete, rehef of mental s5miptoms 
and a progressive gain in weight. Apparently these 
good results were due to the improvement in general 
nutrition — the brain benefiting indirectly. 

Melalgia Paraesthetica. — ^This is a painful numbness 
of the outer aspect of the thigh. It is due to a neuritis 
of the external cutaneous nerve caused by injury or 
pressure. Pressure by a badly fitting corset may cause 
it. lonisation with salicylic ions is a suitable form of 
electrical treatment. 

Metatarsalgia. — ^The author has seen good results, in 
two cases of metatarsalgia, follow the heating through of 
the feet by diathermy. One patient on which surgical 
operation had been repeated, without lasting benefit, 
improved so much that he was able, after a course of 
treatment, to walk long distances without pain. 

Moles. — Small hairy moles should be treated by re- 
moving the hairs, using the method described under 
Hypertrichosis. The mole will then disappear. If there 
is a pigmentation of the skin much of it will disappear 
after the epilation. If there is much remaining pigment 
it can be removed by destroying the ceUs in which it lies 
by means of zinc ions. A zinc needle is inserted at several 
points for short distances and currents of 2 milliamperes 
passed for one minute for each insertion. 

Moles without hair can be treated by ionising their 
base with zinc, using a zinc needle. The method is 
described under Warts. 



N^VUS 235 

Monoplegic (see Hemiplegia). 

Myalgia. — ^By this is meant muscular pain — ^the result 
of over-fatigue — a condition which is brought about very 
easily in debilitated persons. It is most frequent in the 
trunk muscles and is accompanied by local tenderness 
and increase of the pain on movement. It is foimd, 
most usually, at the origin or insertion of certain muscles, 
the most common of which are the trapezius, spinal 
muscles, pectoraHs major and minor (inframammary 
pain) and rectus abdominis. 

General electrical treatment, by rhythmic sinusoidal 
currents, in the long bath is of value in improving the 
condition of the body and the muscles. Local applica- 
tions of the same current are useful for the treatment of 
the affected muscles only. The constant current, with- 
out rhythmic variation, may also be tried ; the anode 
being placed over the painful area. 

Myelitis. — ^Electrical treatment is beneficial for the 
results of myelitis — e.g. weakness in the lower limbs and 
in the bladder and rectum — and for trophic alterations 
in the skin — e.g. bed-sores. 

The constant current should be applied to the spine ; 
the electrodes should be placed over the vertebral column 
so as to include between them the damaged spinal cord. 
The application of rhythmically varied faradic or 
sinusoidal currents in baths is useful in improving the 
condition of the muscles of the limbs. Bed-sores should 
be treated by zinc ions. 

Naevus. — ^The method of destruction of nsevi by 
electrolysis (described in detail on page 91) has an 
advantage in that it destroys very little of the skin if 
skilfully applied. This makes the method particularly 
valuable when the naevus is wholly or chiefly under the 
skin, and when it is situated on the face or other parts 



236 ESSENTIALS OF MEDICAL ELECTRICITY 

exposed to view. An anaesthetic is required and more 
than one treatment is necessary, unless the naevus is 
very small. The method of treatment by carbon dioxide 
snow was largely used for treatment of naevi, but, in the 
writer's experience, is less satisfactory than electrolysis 
in the case of naevi on the face and scalp. During treat- 
ment by solid carbon dioxide it is very difficult to com- 
pletely destroy the naevus, unless the application is long 
enough to cause destruction of the skin in the region as 
well as the part of underlying tissue. 

Neuralgia. — It is necessary, when using the term 
neuralgia, to have a clear knowledge of what the term 
connotes. The term should be used for those cases of 
pain in the area of distribution of a nerve without any 
morbid condition of that nerve. The pain is a " referred 
pain," referred to the area of skin supphed by the nerve. 
There may be an evident exciting cause. 

When present, it is not on the same nerve or nerve 
branch along which the pain is referred, but on another, 
so that the reference of the pain is a sort of reflex act, 
the afferent and efferent channels being sensory nerves. 
Thus a carious tooth may be a source of irritation 
of the inferior dental branch of the fifth nerve and 
cause a pain to be referred refiexly along the cutaneous 
branches of the trigeminal nerve. Neuralgic pains are 
frequently intermittent pains. Cutaneous tenderness 
is frequently present. A form of electrical treatment 
that is suitable for neuralgia (referred pains) is the 
application of the faradic current by means of a wire 
brush to the skin, so as to produce strong counter- 
irritation. Another method of treatment is the intro- 
duction of ions into the skin. Exciting causes must be 
looked for and removed, if possible. Often there is no 
discoverable cause. 

(i) Trigeminal Neuralgia. — ^Some cases of trigeminal 



NEURITIS 237 

neuralgia benefit greatly by introducing, into the painful 
area of skin, salicylic ions or quinine ions. The affected 
side of the face should be covered by a weU-fitting pad. 

(2) Great Occipital Neuralgia. — ^Neuralgia of the great 
occipital nerve should be treated by ionisation with 
salicylic or quinine ions. 

Neurasthenia. — ^This is a term applied to a class of case 
which is characterised by a sort of nerve exhaustion or 
" nervous debility "^the patients considering themselves 
mentally and physically worn out, as well as the subject 
of some serious organic disease. They are convinced of 
their own inability to discharge the " daily round," and 
in neglecting their usual vocation give themselves up 
to brooding over and magnifying their real or fancied 
disabiUties. 

In the treatment of neurasthenia we should, as far as 
possible, endeavour to improve the moral or mental con- 
dition of the patients by encouraging them to feel more 
confidence in themselves and to assure them that re- 
covery is within their reach. In most cases it is advisable 
for them to give up their usual vocation for a time, which 
may be anything from three months to a year, or even 
more. Complete rest with change of diet and environ- 
ment are very important factors in bringing about a 
cure. 

Electrical treatment may be prescribed as part of the 
general conduct of a case of neurasthenia. General 
stimulation of the body, by means of the sinusoidal cur- 
rent in baths is useful. The form of general stimulation 
of the nerve centre known as " central galvanisation " 
should be tried. 

Neuritis. — ^Electrical treatment is of value for cases of 
neuritis. The way in which it should be appHed de- 
pends upon the degree of pain present. In some cases 
of neuritis the motor nerves are mainly affected and 



238 ESSENTIALS OF MEDICAL ELECTRICITY 

paralysis is the chief symptom. In others the sensory 
nerves are chiefly involved and pain is the chief symptom. 
In neuritis accompanied by pain, the pain may be local- 
ised to the nerve trunk, or it may be felt in the region 
suppHed by the fibres. In the former case the inflam- 
mation affects the nervi nervorum ; in the latter it 
affects the sensory fibres contained in the main trunk 
and its branches. 

Where paralysis without pain is the chief feature, the 
rhythmically varying current should be apphed, the 
electrodes being arranged in positions so that the affected 
nerves and their muscles are included in the treatment. 
The current may be applied to the part placed in a 
bath. The treatment is best given in full-length baths 
when the neuritis is general. The details of the method 
of electrical treatment are described in the chapter 
on the treatment of paralysis. 

When pain is the chief symptom of the neuritis, it 
should be treated by ionisation with salicylic or quinine 
ions. Applications of diathermy, so as to heat through 
the painful part, should be tried. The application of 
gentle rhythmic sinusoidal current in baths is also 
beneficial. 

When the neuritis is due to a general cause the best 
plan is to give the treatment to the whole body, even if 
only one nerve trunk is affected. The general treatment 
is likely to promote elimination of the toxins, and, in 
addition, stimulates the self -defensive action of the body. 

(i) Alcoholic Neuritis. — ^Electrical treatment is not 
prescribed in the acute stage of this form of neuritis 
when there is pain, but when this stage has passed and 
the patient is left with weakened or powerless muscles, 
treatment in the full-length electrical bath with rhythmic- 
ally varying sinusoidal or faradic currents is of value and 
hastens recovery. 

(2) Arsenical Neuritis. — ^Neuritis may be the sequel 



SEPTIC NEURITIS 239 

of a single large dose of arsenic, and it arises when the 
violent acute symptoms that immediately follow the dose 
have subsided. Neuritis may also arise during the 
medicinal appHcation of increasing doses of arsenic, with 
or without general symptoms (salivation, nausea, vomit- 
ing, etc.). Electrical treatment may be given, with 
benefit, when the acute stage has passed, on the lines 
already laid down. 

(3) Brachial Neuritis. — ^This is a neuritis that in- 
volves the brachial plexus, either the whole or one or 
more of its trunks. It occurs after injury or exposure 
to cold, in patients who are predisposed to it by gout, 
alcohol or syphiUs. The latter maladies should receive 
appropriate treatment and electricity should be appUed 
in the form of diathermy or ionisation when there 
is pain. If there is weakness afterwards, rhythmic 
sinusoidal or faradic currents should be appUed. 

(4) Rheumatic Neuritis. — ^This is a clinical form of 
neuritis in which there is no evident cause ; a history 
of exposure to cold and wet is sometimes obtained, but 
this is most probably a predisposing cause. Brachial 
neuritis is, in many cases, a " rheumatic " form of 
neuritis ; so also is sciatica. Facial palsy is frequently 
the result of a " rheumatic " form of neuritis. 

The form of electrical treatment is determined by the 
degree of pain present, ionisation if there is much pain, 
sinusoidal currents if there is, chiefly, weakness. 

(5) Septic Neuritis. — ^This is a form of neuritis that 
occurs in parts that are the seats of septic infection. The 
exciting cause is no doubt the infecting organism. It 
is seen in cases of bullet and shrapnel wounds that have 
become infected, and it sometimes occurs in parts that 
have been the seat of abscesses. It seems possible 
that toxins absorbed from septic foci may cause neu- 
ritis in parts at a distance. Lewis Jones mentioned 
a case in which facial paralysis, accompanied by pain 



240 ESSENTIALS OF MEDICAL ELECTRICITY 

and numbness on the same side of the face, followed 
confinement attended by sepsis. 

Recovery in cases of septic neuritis is very slow. 

Lewis Jones recommended the use of the constant 
current in the limb baths. The cases that have been 
sent to the writer for treatment of septic neuritis in 
soldiers following bullet and shrapnel wounds have de- 
rived benefit from the constant current, applied through 
moistened pads or in the Schnee bath. 

Neuritis may occur after many of the specific fevers. 
General electrical treatment in baths is useful in such 
cases. Neuritis is liable to occur in syphilis, the poison 
of the latter being especially prone to attack nerve tissue. 
Electrical treatment should be given in conjunction with 
anti-syphilitic remedies. Neuritis may also occur after 
gonococcal infection. 

Nocturnal Incontinence (see Incontinence). 

Obesity. — ^Bergonie has introduced a new electrical 
method for the removal of superfluous fat. A faradic 
current is used to rhythmically tetanise the limb and 
trunk muscles and make them work against resistance. 
The current from a specially designed induction coil 
IS taken through a mercury metronome in which it is 
interrupted about sixty times each minute. It is then 
distributed to separate pairs of electrodes, which are 
appUed to the body and include between them different 
groups of muscles. The strength of current passing to each 
pair of electrodes is regulated by a variable resistance. 
The resistances are mounted on a switch-board. Of the 
electrodes, four are metal plates fixed to a special reclining 
chair, two to the back, two to the seat. They are covered, 
each separately, with towels soaked in hot water. When 
the patient sits on the chair his shoulders and back are 
in contact with two of these electrodes, his buttocks and 
thighs with the other two. His legs and forearms are 



ORCHITIS AND EPIDIDYMITIS 241 

suitably supported on rests. Other electrodes are made 
of metal plates. They are apphed to the forearms, 
abdomen, thighs and legs, with pads of moistened lint 
intervening, and secured in position by straps. When 
the apparatus is set in action the various muscle groups 
contract rhythmically and simultaneously, sixty times 
each minute. The movements of the limbs and other 
parts are resisted by sand-bags placed on the abdomen 
and front of legs, thighs and forearms. The total weight 
of these bags may reach 100 lb. or more. As a result 
of the large amount of work passively done by the 
muscles, the patient sweats profusely and gives off large 
quantities of heat, and excess of carbon-dioxide is ex- 
haled. The pulse-rate increases and the blood pressure 
falls. 

Treatment should be given daily, for periods of twenty 
minutes at first, afterwards increasing the sessions to 
thirty minutes or more. A loss of weight of three to five 
pounds a week may be expected. A large appetite may 
arise as the weight diminishes and must be controlled. 

Occupation Spasm (see Writer's Cramp). 

CEJsophageal Spasm. — This condition of muscular 
spasm of the oesophagus without organic stricture may 
be treated by passing the faradic or galvanic current 
between electrodes placed, one on the spine over the 
oesophagus and the other on the front of the chest. 

CEsophageal Stricture (see Chapter VI., page 96). 

Orchitis and Epididymitis have been successfully 
treated with the constant current with the electrodes 
placed on the front and back of the scrotum. In the 
acute stage but very mild currents can be borne — | to i 
milliampere. In the chronic stage 10 or 20 milliamperes 
may be employed. The electrodes may be moistened 
with potassium iodide solution, and then the iodine ions 

Q 



242 ESSENTIALS OF MEDICAL ELECTRICITY 

which migrate in from the negative electrode may have 
some therapeutic action. 

Ophthalmia Neonatorum. — ^A case treated by zinc ions 
was reported by Ramsden. A cotton-wool pad soaked 
in a 2% solution of zinc sulphate was placed on 
the front of the cornea and sclerotic. A current of 0*5 
milliampere was passed for three minutes. The treat- 
ment was repeated twelve hours later. In two days the 
ophthalmia was cured. 

Optic Neuritis. — Cases have been reported in which 
improvement has resulted by passing the constant 
current transversely from temple to temple and longi- 
tudinally between the front of the eye and the back of the 
head. Small currents are used — 2 milUamperes. 

Ovarian Neuralgia. — ^This may be treated by passing 
the constant current between the front of the abdomen 
where the pain is felt and the back. Large currents, of 
40 to 50 miUiamperes, should be used. 

Ozsena. — ^High-frequency treatment with a vacuum 
electrode introduced into the nasal cavity has been 
recommended and good results have been reported, 
lonisation with copper ions has produced good results. 
The cavity on each side is packed with cotton-wool 
soaked in 2% copper sulphate solution, and a copper 
wire is embedded in the wool without touching the 
mucous membrane anywhere. Currents as strong as 
can be borne by the patient without pain should be 
appUed for fifteen minutes. 

Paralysis. — ^The electrical treatment of paralysis is 
considered in Chapter IX. 

Paralysis Agitans. — ^The writer has seen considerable 
improvement in three cases of this disease following 
general diathermy. In two patients, electrodes were 



PLEURISY 243 

grasped by the hand ; in the third the treatment was 
appUed on the Schittenhekn condenser couch. The 
tremors diminished and the gait improved and there was 
a gain in general health. The improvement was main- 
tained for some weeks after the treatment was left off, 
but ultimately the symptoms recurred. Treatment was 
given for periods of twenty to thirty minutes, twice 
Weekly. 

Paraplegia (see Hemiplegia). 

Perineuritis. — This is an inflammation of the sheath 
and interstitial connective tissue of a nerve trunk. The 
pain is probably due to irritation of the nervi nervorum — 
i.e. the nerve fibres that supply the sheath and connective 
tissue. The electrical treatment should take the form of 
diathermy, or ionisation with quinine or salicyUc ions, 
as mentioned under Neuritis. 

Piles may be treated by zinc ionisation. A method 
was described by Bokenham (Proc. Roy. Soc. Med., 
vol. ii., section of Electro-therapeutics, page 135). The 
pile is transfixed with a zinc needle previously amalga- 
mated by dipping it for a moment first in water, then in 
dilute sulphuric acid, then in mercury. The needle is 
connected to the positive pole. An indifferent electrode 
is placed under the hip, the patient lying on his side. 
The current is very slowly increased, till, after ten 
minutes, it reaches 25 milliamperes. The pile changes 
in colour from a red or blue-red to a yellow or grey- 
yellow. Then the current is diminished, with equal 
slowness, to zero. Before the pile is transfixed, 10% 
cocaine is applied on a pad, and then cocaine (5%) and 
adrenalin are injected. After ionising one portion there 
should be an interval of ten days. 

Pleurisy. — ^Pleural adhesions may be treated by 
chlorine ions (Leduc). Large electrodes are used, placed 



244 ESSENTIALS OF MEDICAL ELECTRICITY 

on each side of the chest, and one should be of sufficient 
size to cover nearly the whole of the affected side. The 
other should be placed on the other side. Strong cur- 
rents should be applied for long sittings and frequently 
repeated. 

Port- Wine Marks. — These may be treated by the 
method of surgical ionisation, described in Chapter VI., 
under Nsevi. They may also be treated by high-frequency 
sparks directed on to the surface of the overlying skin 
from a metal point electrode connected to the solenoid. 
Erythema and vesication foUow, and obliteration of the 
port-wine mark frequently follows. 

Prostatic Enlargement. — ^The static wave current has 
been recommended for enlargement of the prostate, but 
only when the enlargement is due to congestion. A 
special electrode is used and is placed in the rectum in 
apposition with the prostate. See page 207. 

High-frequency treatment on the condenser couch 
with a metal electrode in the rectum has been 
recommended. 

Pruritus of the anus and vulva may be treated success- 
fully in some cases by the static breeze, or by the high- 
frequency effluve. The glass vacuum electrode may be 
used either with the high-frequency or the diathermy 
machine. 

In some cases iodine ions are successful. A 2% 
solution of potassium iodide is used. A circular aper- 
ture is cut in a piece of waterproof cloth and applied 
to the skin between the buttocks, so that only the affected 
part around the anus is exposed. A lint pad soaked in 
the solution may then be applied over the aperture. In 
this way iodine ions will gain entry only into the part 
desired. 



RODENT ULCER 245 

Pyorrhoea Alveolaris. — This may be treated by zinc 
ions. A zinc needle with a thin layer of wool wrapped 
round it, soaked in 2% zinc sulphate solution, is in- 
sinuated between the gum and the root of the tooth. 
Only a very small current can be borne, J to i milliam- 
pere. On subsequent applications it may be strengthened. 
The current is passed from a half to one minute. The 
current must be increased very gradually and evenly, on 
account of the tenderness of the part. When the current 
is derived from a portable battery of cells a shunt resist- 
ance must be used, so that the current that is to be applied 
to the teeth can be gradually and evenly regulated. 

Raynaud's Disease. — ^Electrical treatment does not 
prevent the onset of the paroxysms of this disease, but 
if the affected limbs are immersed in a bath and subjected 
to the galvanic current during a paroxysm it is said that 
the duration of the attack is lessened. 

Rectal Fistula (see Fistula). 

Rheumatoid Arthritis (see Arthritis). 

Rickets. — Children suffering from rickets are not 
usually sent for electrical treatment, but improvement 
quickly follows the general stimulation of the body pro- 
vided by the rhythmic sinusoidal current in the electric 
bath. Lewis Jones spoke highly of this method of 
treatment. 

Rodent Ulcer. — ^This may be treated by ionisation with 
zinc ions, and the method is more particularly indicated 
in the early cases. The surface of the ulcer is cleaned 
with a 2% solution of zinc sulphate after removing 
any crusts or discharge. A pad of lint, cut to fit the 
ulcer and slightly overlapping its edges, is applied to 
it. A zinc disc, bearing a terminal for the conducting 



246 ESSENTIALS OF MEDICAL ELECTRICITY 

wire, is pressed against the pad. The current is passed 
for fifteen minutes. It is very gradually increased till it 
is as strong as the patient can bear. The tissue under- 
lying the pad becomes pearly white. The treatment 
need not be repeated till fourteen days have elapsed, and 
only if the ulcer fails to fiU up. 

For chronic rodent ulcers and ulcers that have de- 
veloped again after they have healed under former treat- 
ment, diathermic cautery is recommended. The writer 
has seen one case of rodent ulcer that proved to be in- 
tractable to all other methods of treatment heal under 
the influence of diathermic cautery. He has also treated 
one case of rodent ulcer in the pre-ulcerative condition, 
by diathermic cautery under local anaesthesia. The 
growth sloughed away and, six months later, had not 
recurred. It is too early yet to speak of the permanence 
of the results obtained by diathermic cautery. The 
method should receive further trial. For details of the 
method see Chapter XII., under Surgical Diathermy. 

Sarcoma (see Malignant Growths). 

Scars. — ^The scar tissue that is formed after chronic- 
inflammatory processes can be softened and rendered less 
tense by ionisation with chlorine ions, provided the cause 
responsible for it is no longer present. Adhesions in 
joints can be loosened in this way. The writer has seen 
the cicatricial contraction that foUowed a Halsted opera- 
tion and prevented abduction of the arm disappear after 
twelve sessions of ionisation with chlorine ions and full- 
range movement of the arm return. After destruction of 
tissue — e.g. by burns — the scar tissue that forms can be 
rendered soft and supple. Good cosmetic results follow 
after treatment of scars following burns by this method. 
It is necessary to be patient. If treatment is given 
thrice or twice weekly, six or eight weeks must not be 
considered a long period. 



SCIATICA 247 

Sciatica. — ^Electrical treatment of sciatica is not likely 
to be successful if, from improper or neglected treatment 
in the early stages, scar tissue has formed in the sheath 
and perineural connective tissue and has compressed the 
nerve fibres. It is most likely to be beneficial when the 
nerve trunk is in an earlier stage and organic changes 
have not taken place. After the early acute stage has 
passed the electrical treatment may take one of three 
forms. lonisation with quinine ions or salicylic ions 
may be tried. The pads must be large. One, four 
inches wide, should be placed on the back of the thigh 
and extend from the back of the knee to the sacrum. 
The other, of a similar size, should be placed on the front 
of the thigh and abdomen. 

Diathermy may be tried. Nagelschmidt recommends 
the following method. A small electrode is placed over 
the nerve in regions that are tender on pressure. The 
indifferent electrode is placed on the opposite side of the 
limb. A current of J to i ampere is passed for five 
minutes, so as to heat the nerve without burning the 
skin. Other tender regions are heated in the same way, 
each for the same time. After the diathermy, he uses 
high frequency and applies it with a condenser electrode. 
Nagelschmidt uses a thick glass tube electrode filled with 
graphite. With this he presses into and around the 
region of the nerve in its various parts, breaking down 
adhesions if present. 

A third method of electrical treatment is the applica- 
tion of the rhythmic sinusoidal current in fuU-length 
baths. If the application is painful the other method 
should be appHed first and the third method appHed 
later. 

In cases where cicatricial tissue has developed, 
chlorine ionisation may be tried. Some writers recom- 
mend the static wave current. Surgical operation may 
be necessary. 



248 ESSENTIALS OF MEDICAL ELECTRICITY 

Sexual Disorders. — ^Electricity has been much used in 
sexual disorders, but it has not proved of great value. 

Most sexual disability is due either to nervousness or 
over-indulgence, and it is not easy to see how electricity 
locally applied could, under such circumstances, have 
any great value. Erb, however, has advised the use 
of the constant current, from 5 to 10 milliamperes. 
A small button-shaped electrode, positive, to the 
perinaeum, and the other larger electrode to be moved 
up and down slowly over the lower dorsal and lumbar 
spine. Faradisation of the scrotum with a fine wire 
metal brush is sometimes of value in cases of impotence. 

Sinuses. — Sinuses that refuse to close should be treated 
by the ionic method, using zinc, or salicylic ions, or the 
ions in a solution of iodine in potassium iodide. The 
method of application is described in Chapter V., page 83. 

Sprains (see Arthritis— Injuries of Joints). 

Spring Catarrh (Vernal Conjunctivitis). — This very 
intractable infection of the conjunctiva is sometimes 
sent for electrical treatment. lonisation with quinine 
ions has been recommended. 

Stellate Veins (see page 94). 

Stiff Joints (see Arthritis— Injuries of Joints). 

Stricture (see page 95). 

Sycosis. — ^This may be treated by ionising the sup- 
purating follicles with copper or zinc, needles of these 
metals being introduced into the affected parts. The 
whole of the affected skin should afterwards receive zinc 
ionisation from a pad covering the part. 

Synovitis. — Chronic synovitis may be treated by 
ionisation with salicyUc or iodine ions. 



ULCERS 249 

Tabes (see Locomotor Ataxy). 

Tinea Tonsurans. — The fungus in the hair roots can 
be destroyed by ionising the scalp with copper or zinc 
ions. It is impossible to remove every trace of grease 
from the scalp and hair follicles, and unless this be done 
some hairs will remain infected and afterwards reinfect 
the scalp. When there is only one small affected patch 
the ionic method of treatment may be tried. After a 
thorough wash of the scalp with soap and water, followed 
by alcohol and ether, a pad soaked in 2% zinc sulphate 
or copper sulphate is placed in contact and allowed to 
stop there for half-an-hour. The pad is then connected 
to the positive pole, and the current started, so that the 
ions can migrate inwards. 

Tinnitus Aurium sometimes responds to electrical 
treatment very satisfactorily. A bifircated electrode is 
used and made the anode. The electrode is like the 
metal part of a binaural stethoscope. To its free ends 
are attached the pads. The latter are placed behind the 
ears. The current must be turned on and off very 
gradually or the noises may return worse than before. 

The brush discharge from the static machine and 
the high-frequency effluve, applied locally, have been 
recommended. 

Trachoma. — ^W. J. Morton originally reported a 
method of treatment of trachoma by copper ions. A 
copper rod was slowly passed over the everted lid and 
a current of 2 to 3 milliamperes or more was passed for 
two or three minutes. Four to twelve treatments were 
necessary. Several cures were reported. 

Ulcers. — (i) Chronic Non-Specific Ulcers improve at 
once under ionic treatment and heal rapidly. The zinc 
ion is generally chosen. Occasionally the zinc fails. 
It is then advisable to apply a solution of iodine in 



250 ESSENTIALS OF MEDICAL ELECTRICITY 

potassium (i% of each) and introduce into the ulcer 
the negatively charged ions from this solution. The 
salicylic ion is sometimes effective when the zinc ion 
fails. The ionic method of treatment of these ulcers will 
often succeed when all other methods have failed. When 
the zinc ions are used the base and edges of the ulcer take 
on a pearly white hue. No further treatment should be 
given as long as this appearance is maintained, and so 
long as the edges of the ulcer are growing towards each 
other it is not necessary to repeat the treatment. If 
the iodine ions or salicylic ions are used they need not be 
applied again till a week has elapsed, and then only if 
the ulcer ceases to fill up. 

(2) Corneal Ulcer (see page 224). 

(3) Rodent Ulcer (see page 245). 

Urinary Incontinence (see Incontinence of Urine). 

Variocele. — ^The pain associated with variocele is 
reheved by the appUcation of high frequency to the 
scrotum. Diathermy would probably be more efficacious. 
The patient lies on the condenser couch (Schittenhelm 
couch when diathermy is applied). The scrotum is 
enveloped in strips of lint soaked in 10% salt solution, 
and an electrode, made of thin lead plate, is bent so as 
to fit the Hnt surrounding the scrotum. 

Varicose Veins. — ^These may receive high-frequency 
or diathermic treatment on the condenser couch or 
Schittenhelm couch respectively. The veins should be 
covered with lint strips soaked in 10% saline, and lead 
plates should be laid over these and connected to the 
diathermy or high-frequency machine. 

Vernal Conjunctivitis (see Spring Catarrh). 

Writer's Cramp. — ^The electrical treatment of this is 
unsatisfactory, even if the occupation is left off. The 



WARTS 251 

passage of a constant current from the back of the neck 
to the forehead may be tried. Another method is to 
apply the same current, but to direct it from the hand 
to the back of the neck. The anode is placed on the 
palm if the cramp is of the extensors ; on the dorsum if 
it is of the flexors. A current of from 2 to 8 milliamperes 
is to be applied twice daily, for fifteen to twenty-five 
minutes. Complete rest from writing is absolutely 
essential. 

Other forms of " occupation spasm " are to be treated 
in the seime way, the anode placed opposite the affected 
muscles. 

Warts. — ^Flat warts can sometimes be made to dis- 
appear by introducing magnesium ions into them. A 
pad soaked in 5% magnesium sulphate is placed 
over the region covered by the warts. One or two 
applications, only, are necessary. If the method is not 
successful ionisation with zinc should be tried. Each 
wart is transfixed at its base, at the level of the surround- 
ing skin, with a zinc needle. A current of i milliampere 
should be applied for one minute. If the wart is 
larger than, say, an eighth of an inch in diameter, it 
should be transfixed twice, in two directions, at right 
angles. If stiU larger, three or four times, parallel to 
each other. The wart darkens in colour and drops off 
after about a week. A current of i milliampere for one 
minute is sufficient for each application. 



CHAPTER XV 

PHYSICAL PRINCIPLES 

Nature of Electricity. — Very little is known of the 
actual nature of electricity. The question is, however, 
of minor importance in the application of electricity 
in medicine and the arts, since we are here concerned 
entirely with the effects to which it gives rise, not with 
the nature of the agent that is responsible for their pro- 
duction. It is necessary, however, that certain funda- 
mental principles should be borne in mind regarding our 
conceptions of electricity. 

In the first place it must be remembered that electricity 
exists ever5Avhere, permeating all matter, but in a con- 
dition of such even distribution and perfect balance that 
we are unaware of its existence. When the distribution 
is altered the effects which are termed " electrical " are 
then made manifest in the effort to regain the balance. 
In the second place, it must be remembered there is no 
creation of electricity, although it is convenient to make 
use of such an expression. We merely alter its distribu- 
tion, producing in one part an excess, in another part a 
deficit ; hence the origin of the expressions " positive 
charge " or " positive electricity," and " negative 
charge " or " negative electricity." It must also be 
remembered that the subdivision of electricity into 
various forms, such as static electricity, current electri- 
city, etc., does not imply the existence of so many 
varieties of electricity, but refers to the different ways in 
which it can manifest itself. 

Of the views that were held concerning the nature of 

252 



NATURE OF ELECTRICITY 253 

electricity itself, one was that it consisted of an " im- 
ponderable fluid " pervading aU matter, but that, so long 
as the distribution was even, neither an excess nor a 
deficit, there was no outward and visible evidence of it. 
If the balance was upset, then the effects termed electrical 
came into evidence. The expressions " positive elec- 
tricity " or " positive charge " indicated the idea that 
the fluid was present in excess ; " negative electricity " 
or " negative charge " that it was present in amount less 
than that in the state of even distribution. This is the 
" one-fluid theory " of the nature of electricity. 

The modern view is that electricity is a material 
substance consisting of units or atoms that are irsVirt^ ^^ 
the size of an atom of hydrogen. Each atom of matter 
is supposed to contain one or more of these units, or 
" electrons," as they have been called. A body which 
contains the normal number of electrons presents no 
electrical properties. It is only when there is an excess 
or deficit of electrons that these properties become mani- 
fest. When glass is rubbed with silk it is supposed, 
according to the old theory, to have acquired excess of 
the electric fluid, or, in other words, a positive charge. 
Now when a body loses some of its electrons it shows 
the same electrical properties as a positively charged 
body, and vice versa. It is therefore unfortunate that 
the term " positive " was arbitrarily chosen to express 
the electrical condition of a body which, according to 
modern research, contains a deficit of electrons. 

In order to avoid confusion the terms positive and 
negative are used in their original meaning ; the charge 
on glass after the latter has been rubbed with silk is 
regarded as a positive charge. 

A. Static Electricity 
Static electricity is most readily produced by friction. 
If glass is rubbed with silk both acquire an electrical 



254 ESSENTIALS OF MEDICAL ELECTRICITY 

charge. Speaking more correctly, the friction brings 
about a redistribution of electricity, one of the rubbed 
bodies acquires an excess of electricity, the other losing 
it to a corresponding amount. It is commonly supposed 
that the glass acquires the excess, the silk thereby losing 
it to an equal degree. The glass is therefore said to be 
positively charged, the silk to be negatively charged. 
Bodies that are electrically charged acquire new pro- 
perties, the most characteristic of which is their power of 
attracting or repelling other Ught bodies. It can easily 
be shown that they attract other objects that are hght 
and free to move. It can also be shown that a positively 
charged body will attract a negatively charged body, 
but that two positively charged bodies, or two negatively 
charged bodies, will repel each other. Bodies that are 
similarly charged, therefore, repel each other, and those 
that are differently charged attract each other. These 
properties of electrified bodies are demonstrated by the 
electroscope. This instrument is used for the purpose of 
finding out whether an object is electrically charged or 
not, and whether the charge is negative or positive (see 
page 257). 

Many other bodies besides glass and silk become 
electrically charged by friction. The same two bodies 
always take the same charges when rubbed together. 
The charge which a body takes depends upon the sub- 
stance against which it is rubbed, and the charges on the 
two are always equal and opposite. It is possible to 
construct a list of substances so that when any pair of 
them is rubbed together the body higher in the hst is 
positively electrified and the other is negatively electrified 
to an equal extent. The following is a list of this kind : 
catskin, glass, flannel, paper, silk, shellac. 

If we rub glass with catskin the glass becomes nega- 
tively electrified, while if the same piece of glass is 
rubbed with silk it is positively electrified. 



CONDUCTORS AND INSULATORS 255 

The electrical charges that are produced by friction 
remain on the bodies which are rubbed together, and 
do not at once flow off. The term " static " is apphed 
to such electrical changes to signify that the electricity 
stays where it is produced. The term conveys the idea 
of electricity " at rest." Speaking more precisely, the 
distribution of electricity rendered uneven, in excess on 
one body, in deficit on the other, remains uneven ; the 
balance has been upset and it remains upset. 

Many substances (they were formerly called non- 
electrics) do not become electrically charged when 
rubbed together. The reason is because they allow the 
ready passage of electricity along them and from one to 
another, so that the balance is restored as fast as it is 
upset, if indeed it can be said to be upset at aU. These 
substances are conductors of electricity. Other sub- 
stances do not allow the ready passage of electricity 
along them, so that the balance, upset by friction, is 
not readily restored. The latter substances, formerly 
grouped together as " electrics," do not conduct elec- 
tricity, and are now known as " non-conductors " or 
" insulators." 

CJonductors and Insulators. — ^There is no sharp line of 
demarcation between conductors and non-conductors. 
All substances are conductors of electricity more or less, 
but some of them conduct it so exceedingly badly that 
they are, practically, insulators. A perfect insulator 
would be an absolute vacuum, but as an absolute vacuum 
exists only in theory — being practically unobtainable — 
we are at present without a perfect insulator. 

The metals are good conductors. So also is carbon. 
Aqueous solutions of acids, alkahes and salts are less 
good conductors. The tissues of the body that contain 
salts in solution conduct electricity fairly well. Vulcanite, 
ebonite, shellac, sealing-wax, glass, silk are insulators. 



256 ESSENTIALS OF MEDICAL ELECTRICITY 

Distilled water is an insulator. The skin, when moist, 
is an indifferent conductor. When dry it is a very bad 
conductor. The conduction of electricity by fluids and 
by the tissues of the body forms a subject of extreme 
importance for the correct understanding of the action of 
electricity on the body and was considered in Chapter I. 

The conducting power of some substances varies with 
their physical state. For instance, metals when heated 
do not conduct as weU as they do when they are cold. 
Carbon, on the other hand, conducts better as its tem- 
perature is raised. Absolutely pure water is a very good 
insulator, but the addition of a slight trace of a salt 
brings down the resistance enormously. A person's 
skin when dry has a very high resistance, but when well 
wetted becomes a very fair conductor ; again, dry air is 
one of the best insulators we know of — ^moist air is a poor 
conductor. Further, the insulating power of air is in- 
creased as its pressure is increased, while, on the other 
hand, as the pressure is decreased its insulating pro- 
perties are decreased until a degree of diminution of 
pressure is reached when it becomes a moderately good 
conductor. Further reduction of the pressure now 
increases the resistance, and when the pressure falls to 
zero electricity cannot be conducted at all, a perfect 
vacuum being a perfect insulator. The conduction of 
electricity by the so-called vacuum electrodes used in 
medicine illustrates the fairly good conduction of electri- 
city along air at a certain degree of diminution of pressure. 

In the application of electricity for medical purposes 
we have to deal mainly with the conduction of electri- 
city through fluid conductors. The subject thus becomes 
extremely important, and, when it is clearly understood, 
a ready explanation is obtained of one of the modes of 
action of electricity in producing physiological and thera- 
peutic effects on the body. The matter was considiered 
in detail in Chapter I. 



INDUCTION 257 

When a conductor is mounted on some insulating 
material and not in contact with any conductor, it 
is said to be " insulated," because electricity when 
produced on it cannot escape. 

Induction. — ^When an electrically charged body is 
brought near a conductor, without touching it, the latter 
becomes electrically charged itself. The first body is 
said to induce electricity on the second. The first body 
does not part with any of its charge. It induces a re- 
distribution of electricity on the second body, one part 
of the latter acquiring more than normal (a positive 
charge), another part therefore containing less than its 
normal amount (a negative charge). These two induced 
charges take up definite positions. Suppose that the 
original body was positively charged : since like charges 
repel each other and unlike charges attract each other, 
the negative induced charge takes up a position on the 
second body as near as possible to the first. The positive 
induced charge is repelled as far away as possible from 
the first. If the first body is now removed, the two 
induced charges neutralise each other — i.e. the distribu- 
tion again becomes uniform and the second body now 
shows no sign of an electrical charge. Supposing that 
the second body is insulated : if the first body is again 
approached the charges are again induced. If the 
second body is now momentarily connected to earth, say 
by touching it, the positive induced charge is now re- 
pelled to earth. If the first body is now removed, the 
second body is now left with a negative charge upon it, 
because the repelled positive charge cannot return as the 
second body is insulated. 

The phenomena of induction and of attraction and 
repulsion can be well shown by the electroscope. 

The Electroscope. — In its simplest form this instrument 
consists of two gold leaves suspended from the tip of a 



^x Posit ivsly 
cKarg«cL 

Oody 



258 ESSENTIALS OF MEDICAL ELECTRICITY 

vertical metal rod. They lie in contact, face to face. In 
order to protect them they are enclosed in a glass jar, the 
mouth of which is closed by a cork, through which 'the 
metal rod passes, so that the leaves hang freely within 
the jar. The other end of the rod is outside the jar, and 
it bears a metal ball (Fig. 62). 

When a charged body is brought near fhe metal ball a 

charge of opposite nature is 

induced on the latter and an 

equal charge, of the same 

nature as that on the charged 

body, is repelled to the gold 

leaves. The latter, being 

similarly charged, repel each 

<~ir> \:^ other and diverge. When the 

\_ JL nJ charged body is removed the 

'^'^ '' ^ induced charges neutralise 

each other and the leaves fall 
together again. But if the 
metal ball is momentarily 
touched before the charged 
body is removed the induced 
charge that is repelled to the 
gold leaves is now repelled 
to earth and the leaves, being 
faU together. If now the 




Gold 



Gold leaves 

positively 

charged 

(by induction) 



Fig. 62. — Electroscope 



now no 



longer charged, 
original charged body is removed, the charge that was 
induced on the baU now spreads itself over the metal rod 
and the leaves. The latter diverge once more. Suppose 
that the original body was positively charged, the leaves 
would then be negatively charged. If now a second 
charged body, the nature of the charge being unknown, 
be brought near the ball without touching, it will induce 
on to the leaves an extra charge of the same nature as 
that on itself. If the leaves diverge still further, the 
extra charge on the leaves is of the same nature as that 



DENSITY: POTENTIAL 259 

pre-existing on it — viz. negative. The unknown charge 
is therefore negative. But if the leaves approach one 
another the unknown charge is positive. 

Density : Potential. — ^An electrical charge resides only 
on the surface of a conductor. The density of a charge 
is tha amount of electricity per unit of surface area. If 
the electricity is not evenly distributed over the surface, 
the density must vary in different parts. The distribu- 
tion is even only over the surface of a sphere, and so the 
density is the same all over. If the surface of a conductor 
is not even, the distribution of the electricity wiU be 
uneven ; it wiU be more concentrated on the parts that 
are more convex, while the greatest concentration will 
be on edges and points. The density wiU therefore be 
greatest at edges and points, and here the electricity 
tends to leak off from the conductor. 

The term " potential " is frequently used in reference 
to electrical charges. Conductors are said to be charged 
to a high potential or to a low potential. The potential 
of a charge does not refer to the actual quantity of electri- 
city, but to the quantity in relation to the surface area 
of the conductor on which it resides. The following 
comparison may make the meaning of potential clearer. 
A certain quantity of air pumped into an inexpansible 
vessel would exert a certain pressure on the walls ; if 
the capacity of the vessel was reduced to one half, the 
same quantity of air (measured in the uncompressed 
state) would exert double the pressure, although the 
quantity of air would be the same. In the case of the 
electrical charge, a certain quantity of electricity would 
charge a conductor to a certain potential. The same 
quantity of electricity would charge a conductor of half 
the capacity to double the potential. In the latter case 
the density of the charge — i.e. the quantity of electricity 
per unit of area — is doubled and the result is that the 



26o ESSENTIALS OF MEDICAL ELECTRICITY 

electricity is at a higher potential or " pressure " ; the 
electricity has a greater capacity for doing electrical work 
and overcoming resistance. Electricity at high potential 
flows or tends to flow to parts where it exists at lower 
potential, and if . the diflerence of potential is high it 
may overcome the resistance of the air — that is, if air 
separates the two conductors charged to different 
potentials — and pass across in the form of long sparks. 

The potential of the earth's surface is taken as zero. 
All bodies that are connected to earth by conductors (or 
" earthed ") must be at the same zero potential. 

Positively charged bodies may be regarded as bodies 
charged to a potential above zero ; negatively charged 
bodies as those charged to a potential below zero. 

Capacity. — The quantity of electricity that a con- 
ductor is capable of receiving is determined by the 
" capacity " of the conductor. As the electricity resides 
only on the surface, the capacity of a conductor depends 
upon its surface area. For electrical purposes the 
capacity is measured, not by the surface area, but by the 
quantity of electricity required to raise its potential 
from zero to unity. If a unit quantity of electricity is 
required to raise the potential from zero to unity, the 
conductor is said to have a unit capacity. The unit 
of capacity is a " farad." 

When we say that a conductor has a certain capacity, 
it is not to be thought that it is capable of holding only 
a certain fixed charge. The amount of electricity that a 
conductor will hold depends, apart from its surface area, 
on the potential of the source of supply ; if this is suffi- 
ciently high, electricity will pass to the conductor, 
raising its potential till the electricity begins to leak off. 
If, on the other hand, the potential of the source of supply 
is low, electricity will pass to the conductor till the 
potential of the charge on the latter equals that of the 



CONDENSERS 261 

source of supply, and no more electricity can then pass. 
To return to the air pressure analogy. A pump capable 
of delivering air at any pressure will continue to force air 
into a vessel, raising the pressure within it higher and 
higher till the air escapes through a valve ; on the other 
hand, if the pump delivers air at a low pressure, the 
pressure inside the vessel will soon equal that of the air 
supplied by the pump, and then no more will pass in. 

The capacity of a conductor may be greatly increased 
by bringing close to it a second conductor without 
actually touching it, the two being separated by some 
insulating material, such as the air, or glass, ebonite, etc. 
Such an arrangement of conductors is termed a condenser, 
because the first conductor is now able to hold a much 
larger quantity of electricity than it could before the 
second conductor was in close apposition. 

Condensers. — ^A condenser consists of two conducting 
surfaces separated by some insulating material. The 
latter is sometimes called the " dielectric." The capacity 
of a condenser depends on : (a) the area of the conduct- 
ing surfaces — ^the greater the surface the greater the 
capacity ; (h) the thinness of the dielectric — ^the thinner 
the dielectric the greater the capacity ; (c) the material 
of the dielectric — glass gives a condenser a greater 
capacity than the same thickness of air. 

The simplest form of condenser consists of two metal 
sheets of equal size, facing each other, with a layer of 
insulating material of larger area interposed, allowing 
them to come into close apposition without actual 
contact. 

The most familiar form of condenser is the well-known 
Leyden jar (Fig. 63), which in its most common form con- 
sists of a glass bottle which is partially coated inside and 
out with tin-foil, and provided with a stopper of some 
insulating material through which passes a stout wire. 



262 ESSENTIALS OF MEDICAL ELECTRICITY 

On the outer end of this is mounted a metallic knob, and 
from the inner end hangs a length of brass chain sufficient 
to make good contact with the inner coating. Here 
the two tin-foil surfaces are the conductors — sometimes 
called the " armatures " — and the glass the dielectric. 

To charge a condenser one of the conducting surfaces 
is connected to a source of electricity, and the other 
surface is connected to earth. In the case of the Leyden 
jar, the metallic knob is connected to the source of the 
electricity, while the outer coat is brought 
into contact with earth by standing the jar 
on a table, or by holding the jar in the hand, 
grasping the outer coating. The inner coating 
is charged — by conduction — from the source 
of supply, while the outer coating is charged 
by induction, the induced charge of the same 
sign being repelled to earth, that of the 
opposite sign remaining on the outer coat, 
attracted by the charge on the inner coat. 
Suppose that the potential of the source 
Fig. 63.— of supply is +i. The inner coat of the jar 
ey en Jar ^-j^^j^ connected to this source is thereby 
charged to the same potential. But a larger quantity 
of electricity is required to charge it to this potential 
than would be required if the inner coating stood by 
itself. Suppose the potential of the induced charge on 
the outer coat is -J. The potential of the inner coat 
is now i-| or +J. The inner coat is thus brought 
to a lower potential than that of the supply, and, 
therefore, more electricity must pass to the inner coat 
until the potentials are equal. 

To discharge the jar a bent wire is placed with one end 
against the outer coating, and while retaining it there, 
the other end is brought gradually closer to the knob. 
Presently a spark passes and the jar is said to be 
discharged. 




PRODUCTION OF STATIC ELECTRICITY 263 

As a matter of fact it is not completely discharged 
unless the wire has been brought in contact with the knob 
and the outer coating at the same instant, for if we try- 
again to discharge the jar another spark wiU pass, though 
much smaller and shorter than the first. This is due to 
the " residual " charge, as it is caUed. It may be as well 
to mention here that when We discharge a jar the spark 
is not single — passing once only from wire to knob, or 
vice versa ; what appears to be a single spark is reaUy a 
series of sparks passing alternately in opposite directions 
at an enormously rapid rate. The oscillation may, under 
suitable circimistances, reach a frequency of thousands or 
even millions per second. The discharge of a condenser 
is therefore a current of high-frequency oscillation or 
alternation, providing certain requirements in the circuit 
along which the discharge takes place are fulfilled. These 
have been mentioned in the chapter on high frequency. 

The oscillatory discharges of condensers are used for 
electro-medical treatment, and their application forms 
an important branch of modem electro-therapy — ^viz. 
high frequency and diathermy. Condenser discharges 
have been recently introduced for the purpose of muscle- 
testing and treatment of paralysis and other conditions. 

The Production of Static Electricity for Medical 
Purposes. — Static electric machines are used to generate 
a continuous supply of static electricity, and are of 
two kinds, frictional and inductive. The old-fashioned 
revolving glass cylinder, with an amalgamated leather 
rubber and brass collector or prime conductor, is an 
example of the frictional typ^- This type of machine is 
never used for medical purposes, and is now seen only 
in physical laboratories. 

Induction or influence static machines are much more 
reliable, but how they work is not easy to describe or 
understand. 



264 ESSENTIALS OF MEDICAL ELECTRICITY 

The principle may be outlined as follows : — 
A body, A, is charged positively and brought near 
another body, B. B is therefore charged by induction, 
as described under " Induction." B is momentarily 
connected to earth, whereupon the positive induced 
charge escapes, and the negative induced charge remains. 
B and A are now separated from one another. The 
induced negative charge on B is collected and stored 
on another fixed conductor, while the original positive 
charge on A can be used over and over again to induce 
fresh charges. The mechanical energy expended in 
separating the oppositely charged bodies, A and B, is 
converted into electrical energy. 

Two types of influence machine have been described 
in Chapter XIII. 

(B) Current Electricity 

If two conductors at different potentials are con- 
nected by a wire, the difference of potential will be 
equalised and a current of electricity, of momentary 
duration, will pass along the wire. If the conductor 
at the higher potential can be continuously suppHed 
with electricity, a continuous current will flow along 
the wire. Continuous currents of electricity can be 
obtained by chemical, thermal or mechanical methods. 
The currents that are supplied by the different types 
of cell are obtained by chemical methods. Batteries of 
these cells form an important source of electrical supply 
for medical purposes, and the principles on which they 
work wiU be considered first. 

Production of Electrical Currents by Chemical Methods. 

— If two dissimilar metals are brought into contact a 
slight difference of potential is set up between them, that 
of one being raised (positive), that of the other being 
lowered (negative). The degree of difference is always 



PRODUCTION OF CURRENTS 265 

very slight, and it varies according to the metals taken, 
and it does not depend upon the amount of metal or the 
extent of surface in contact. 

Here again it is possible to draw up a Hst of substances 
— ^metals or conductors in this case — each of which will be 
positively electrified when brought into contact with any 
metal succeeding it, and negatively electrified with any 
metal coming before it in the list : 

4- Sodium Copper 

Zinc . Silver 

Lead Platimmi 

Tin —Carbon 

Carbon is not a metal, but is included in this Ust on 
account of its good conducting properties, and from the 
fact that it is now used so much in all branches of electrical 
work. If zinc and copper be brought together, zinc is 
positive and copper is negative, while if copper and 
carbon be brought together, the copper is positive and 
the carbon negative. The more one metal is removed 
from another in the hst, the greater is the difference of 
potential. It will be noticed that those metals nearest 
the + end of the list are the most oxidisable, while the 
reverse holds good for metals at the - end. 

It is impossible, however, to obtain an electrical 
current by simply bringing dissimilar metals into con- 
tact. If the circuit is completed by connecting together 
the free ends of the two metals in contact, either directly 
or by means of a third metal, new contacts of dissimilar 
metals are made and the difference of potential first set 
up would be effaced. Apart from this, the production 
of a continuous current of electricity, by simply bringing 
dissimilar metals into contact, would be impossible, 
according to the principle of the conservation of energy, 
seeing that the metals are not altered or used up. If, 



266 ESSENTIALS OF MEDICAL ELECTRICITY 

however, the two metals in contact are immersed in 
some fluid that is capable of acting chemically on 
one of them or acting more vigorously on one than 
on the other, a continuous current can be produced 
while the chemical action proceeds. Thus if a piece 
of copper and a piece of zinc are fixed together, end 
to end, the copper becomes negatively charged, the zinc 
positively charged. If the joined metals are immersed 
in dilute sulphuric acid, a circuit is now completed and 
an electrical current flows from the zinc, through the 
acid, to the copper, and through the copper into the zinc. 
Simultaneously, the zinc is slowly dissolved by the acid. 
If the joined metals are bent so that only the free ends 
are immersed in the acid, the junction being outside, an 
electrical current will flow as before and in the same 
direction. Such an arrangement is known as a " simple 
voltaic cell." It serves to illustrate the chemical changes 
that occur during the production of an electrical current 
and to explain the meaning of some commonly used 
terms. 

Voltaic Cell. — ^A simple voltaic cell may be constructed 
by filling a beaker with io% sulphuric acid, partially 
immersing it in two strips of metal, one of zinc, the other 
of copper. These strips are placed parallel to each other 
and with one end of each above the surface of the acid. 
If the strips do not touch one another, above or below 
the surface of the acid, the following changes occur. The 
zinc gradually dissolves in the acid, and zinc sulphate 
and hydrogen are formed. The former dissolves, while 
the latter escapes in the form of bubbles. These are 
seen to form and to escape at the surface of the zinc. If, 
however, the zinc is pure it is not dissolved by the acid 
and it undergoes no chemical change till it makes con- 
tact with the copper. If the contact is made outside the 
acid, either directly or by means of a wire, the zinc begins 



VOLTAIC CELL 



267 



to dissolve and the same chemical change takes place. 
The hydrogen bubbles, however, make their appearance 
on the copper, not on the zinc. Some escape from the 
copper to the surface of the acid, but most of them 
adhere to the metal and soon cover it completely. 
While the zinc is dissolving a current of electricity con- 
tinuously passes around the circuit composed of the 
metal strips, their connecting wire and the dilute acid. 




PdsimePLATE 



yvELOfJiicnmTE 



IkeAWEPUfTE 



^ Fig. 64. — Plates and Poles of a Voltaic Cell 

The current starts in the cell where the zinc is in contact 
with the acid. It passes through the acid to the copper 
plate. It then passes up the copper plate, and then 
across to the zinc plate, outside the acid, along the con- 
necting wire. By passing down the zinc to the acid 
again, the passage along the circuit is completed. The 
direction of the current of electricity is indicated by the 
arrows in Fig. 64. 

If impure zinc is used chemical changes similar to 
those described would have occurred, and the current 
would have passed in the same direction. In addition, 
however, small " parasitic " currents would also have 



268 ESSENTIALS OF MEDICAL ELECTRICITY 

been produced. Commercial zinc contains small 
quantities of other metals. There are, therefore, dis- 
similar metals in contact, and when they are immersed 
in sulphuric acid currents are formed in the way 
mentioned in the preceding paragraph. 

Certain names are given to the various parts of a 
voltaic cell, and as they are continually used it is neces- 
sary to be quite clear regarding their meaning. 

In any cell there is an external circuit and an internal 
circuit, a positive plate and pole, and a negative plate 
and pole. It is important to distinguish between plate 
and pole. 

In Fig. 64 that part of the circuit within the fluid of the 
cell is called the internal circuit, while that outside is the 
external circuit. In any circuit or part of a circuit, that 
part from which the current is coming is positive to a 
part to which current is flowing. 

Bearing this in mind, it will be seen that that portion 
of the zinc which is below the level of the fluid is positive 
to that part of the copper which is also below the level 
of the fluid. In the external circuit we see that the part 
of the copper outside the Uquid is positive to the corre- 
sponding part of the zinc. These dry portions of the 
plates are called the poles. If we attach a wire to each 
of these, the free extremities of these wires become the 
poles. 

Thus it will be seen that the wet portion of the zinc is 
the positive plate and the dry portion is the negative pole, 
while the wet portion of the copper is the negative plate, 
the dry portion is the positive pole. This may seem very 
confusing, but it is not reaUy so, and if the student will 
take the trouble to get the idea thoroughly there is little 
chance of his being confused by any of the various 
arrangements of circuits he will meet with in future. 

It is customary when referring to the plates of a 
battery to speak of the poles and not of the plates. The 



POLARISATION 269 

zinc is thus the negative pole and the other element, be 
it carbon, copper, or platinum, is the positive pole. 

The electrical current that flows around the circuits of 
a voltaic cell soon diminishes in strength. It becomes 
feebler and feebler and finally ceases altogether. 

The explanation of this is that by the accumulation of 
minute bubbles on the copper plate the latter is practic- 
ally transformed into a hydrogen plate, which is electro- 
positive to zinc, and tends to set up a current in the 
reverse direction. Also, the film of gas forms a layer of 
high resistance to the flow of the original current. 

A cell in this condition is said to be " polarised." The 
prevention of polarisation is one of the most important 
objects in the design of a useful cell. The great variety 
of cells that have been devised have their origin in the 
various methods that have been adopted to overcome 
this tendency, and thus give as nearly as possible a 
constant current during their period of activity. 

A simple cell like that described is useful for the 
purpose of demonstration, but is of no value for medical 
purposes, because the current so quickly diminishes on 
account of polarisation, and soon falls to zero. Polarisa- 
tion can be prevented in various ways. One way is to 
add an oxidising agent, such as potassium bichromate, 
to the acid solution. The hydrogen is oxidised as soon 
as it is formed. This method is used in the Poggendorff 
cell. In this ceU, known also as the " bichromate " 
cell, carbon is used instead of copper. In the Leclanche 
cell zinc and carbon are used. The zinc is immersed in a 
solution of salammoniac (ammonium chloride) contained 
in a glass jar. The carbon plate is placed inside a 
porous pot and packed tight round it are fragments of 
manganese dioxide and powdered carbon. The porous pot 
thus filled is placed in the jar containing the salammoniac 
solution. When the zinc and the carbon are connected 
by a wire, a current passes from the carbon to the zinc 



270 ESSENTIALS OF MEDICAL ELECTRICITY 

outside the cell, and from the zinc to the carbon inside 
the cell. Fluid is unable to pass through the wall of the 
porous pot, but the electric current readily traverses it. 
The zinc dissolves in the salammoniac solution, forming 
a double chloride of zinc and ammonium, and ammonia 
gas and hydrogen are liberated. The ammonia dissolves 
and the hydrogen is oxidised by the manganese dioxide, 
so that polarisation is prevented. The oxidation is slow, 
so that if the cell is made to give a current continuously 
for several minutes polarisation begins and the current 
begins to diminish in strength. If the cell is allowed to 
rest, the free hydrogen will be oxidised, and the cell will 
then provide a current of undiminished strength. 

Dry Cells. — ^These have almost entirely supplanted 
other cells for medical purposes. They are small and 
clean, and a number can be packed away in a case of 
small dimensions, so that a portable battery is at hand. 
They are really modified Leclanche ceUs, in which the 
solution of salammoniac is replaced by a moist, pasty 
composition. They tend to run down very slowly even 
if they are not used, but they will last from six months 
to two years if their use is not excessive and the best 
types are used. The battery of dry cells in the portable 
cases can be replaced when exhausted, and some makers 
allow 50% of the original price for the old cells in 
exchange for new ones. 

These dry ceUs can be obtained from most electrical 
dealers. 

Leclanche cells have an E.M.F. of about 1-5 volts when 
new, and their internal resistance is from 75 to 1*5 ohms 
— the smaller the ceU the higher the internal resistance. 
They are now almost universally used in portable batteries. 

Accumulators. — ^Accumulators, or storage batteries, 
as they are often called, are the most satisfactory 
means we possess of obtaining electricity from chemical 



ACCUMULATORS 271 

action. The name " storage battery " is not correct. 
We do not store electricity in an accumulator, but if we 
take one that is run down and drive a current through 
it in the opposite direction to the current it gave 
out when working, we can restore the plates to their 
original condition and so give it a new lease of hfe, so to 
speak — ^and so long as we do not charge or discharge the 
cell at a greater rate than that for which it is designed, 
this process can be repeated almost indefinitely. 

An accumulator consists of a vessel containing sulphuric 
acid diluted till its specific gravity is 1200. In the acid 
are immersed lead plates made in the form of grids. Two 
of these plates are negative, one positive. The spaces 
of the grids are filled with a paste composed of htharge 
in the case of the negative plates, and red lead in the case 
of the positive. The plates lie close together, face to 
face, without touching. The internal resistance of an 
accumulator cell is extremely low. Each cell gives 
2 volts under ordinary working conditions and continues 
to do so until about 75% of its charge is spent. If the 
cell be discharged still further the voltage begins to fall. 
It should never be allowed to faU below 1*8, nor should 
it ever be left at this latter figure for any length of time ; 
it should be recharged at once. If this be neglected, a 
white deposit appears on the plates — ^insoluble sulphate 
of lead. This increases the internal resistance and 
diminishes the capacity of the ceU, and it may be safely 
stated that a cell which has once become markedly 
sulphated can never be restored to its original condition. 
All cells have a certain rate of charge and discharge, 
which depends on the size and capacity, and which should 
never be exceeded. The charging current is usually 
about 10% of the fuU capacity. That is, a sixty-ampere- 
hour cell should not be charged with a greater current 
than 6 amperes. This, continued for ten hours, would 
fully charge the cell. 



272 ESSENTIALS OF MEDICAL ELECTRICITY 

The charging of an accumulator should be continued 
until the voltage rises to 2*5 volts per cell. The voltage 
remains at this for a short time only after charging is 
stopped, when it declines gradually to 2 volts. 

Accumulators are also known as " secondary batteries " 
in contradistinction from the " primary batteries " 
as those previously described are often called. Primary 
batteries cannot be recharged like secondary batteries 
when exhausted. 

Bichromate Batteries. — For cautery and working large 
spark coils the bichromate battery is the most easily 
managed where some form of primary cell must be 
used. The plates are of zinc and carbon. They should 
be of large size, placed close together to reduce the 
internal resistance to its lowest limit, and arranged so 
that they may be readily removed from the exciting 
fluid the moment the current is no longer required. 
The zincs must be kept weU amalgamated. The exciting 
fluid is prepared as follows : — i pound of potassium 
bichromate is dissolved in 8 pounds of hot water. Then 
add slowly 2J pounds of strong sulphuric acid, stirring 
constantly all the time. While still hot, dissolve in 
the mixture 3 ounces of bisulphate of mercury. Each 
cell, when freshly charged, has an E.M.F. of 2 volts, but 
this tends to decline as the ceU is used — due to the gradual 
weakening of the exciting fluid. When this becomes 
green in colour it should be thrown out and fresh solution 
put in. These cells should be thoroughly washed and 
cleaned every three or six months, according to size, and 
care taken to remove aU the crystals of chrome alum 
which will be found sticking to the plates and acid 
vessel. The' zinc plates are gradually dissolved as 
part of the action of the cell and will eventually have 
to be replaced. This is not difficult in most forms now 
obtainable. 



ELECTRO-MOTIVE FORCE 273 

The current produced in the ways described — i.e. by 
chemical means — ^is known sometimes as the " galvanic " 
current, sometimes as the " constant " current, by 
reason of its unvarying direction and uniformity of 
strength. The " direct " current is also a constant 
current, but the name " direct " is usually applied to 
it when it is obtained from the main. 

Electrical currents can also be obtained by mechanical 
methods. These will be described shortly. 

The Measurement of Electrical Currents. — ^This is a 
subject of great importance in the application of electri- 
city for treatment and diagnosis. During the flow of the 
current electricity is constantly passing along the circuit, 
and the terms " strong " or " weak," as applied to the 
current, are used in reference to the quantity of electri- 
city that is passing. The strength of an electrical current 
depends upon two factors : (i) the electro-motive force 
and (2) the resistance of the circuit. These terms will 
be explained. 

Electro-motive Force. — Whatever produces or tends 
to produce a transfer of electricity is called electro- 
motive force. Thus, when two electrified conductors 
are connected by a wire, and when electricity is trans- 
ferred along the wire from one to the other, the tendency 
to this transfer which existed before the introduction 
of the wire and which, when the wire is introduced, 
produces this transfer, is called the electro-motive force 
from the one body to the other along the path marked 
out by the wire. 

The water analogy will perhaps help to make this 
clearer. If two vessels containing water be joined by a 
pipe and we increase the pressure in one of them, the 
water will flow from the one in which the pressure is 
greater until the pressure in both becomes equal. Again, 
if the water is at a higher level in one vessel than in the 
s 



274 ESSENTIALS OF MEDICAL ELECTRICITY 

the other, it will flow from the former to the latter until 
the level is the same in both. In the same way when 
any two electrified bodies are joined together by a 
wire, electricity will flow from the body on which the 
charge exists at high potential to the body on which 
the charge exists at lower potential. The inherent force 
which starts and maintains the current is what is known 
as electro-motive force — briefly written E.M.F. The 
potential of the earth is always taken as the zero of 
electric potential. 

The unit of E.M.F. is the "volt." A single Daniell 
cell produces an E.M.F. that is very slightly greater than 
one volt. 

Resistance. — ^It has already been mentioned that 
different substances vary enormously in their power of 
conducting electricity, some conducting it readily, others 
so badly that they are practically non-conductors or 
insulators. However well a substance conducts electri- 
city there is always some resistance to the flow. 

The resistance of a conductor depends on certain 
conditions. 

It varies 

{a) Directly as the length. 

{b) Inversely as the area of the cross section. 

(c) With the nature of the material of which the con- 
ductor is made. 

{d) To a certain extent with the temperature. 

{a) and (b) are sufficiently obvious. With regard to 
(c), a conductor made of silver is found to have a lower 
resistance when compared with one made of any other 
material of similar shape and size. The resistance of 
copper is very slightly greater than that of silver. 
Platinum has a resistance about six times greater than 
that of silver and iron about nine times greater. 

As a rule alloys have a resistance much greater than 



OHM'S LAW 275 

pure metals. An alloy known as German silver has a 
resistance about fourteen times greater than that of silver, 
while another called rheostene has about forty-four 
times the resistance of copper. Speaking generally, 
the resistance of metals increases with an increase in 
temperature. Carbon and aqueous solutions of salts, 
acids and bases decrease in resistance as the temperature 
rises. 

In speaking of resistance it is useful to have a unit so 
as to be able to compare the resistance of various circuits 
or the different parts of a single circuit. The unit of 
resistance is called the "ohm," after the scientist who 
formulated the law which is known by his name. An 
ohm is represented by the resistance of a column of pure 
mercury at 0°C. of a uniform cross section of one square 
millimetre and 106 centimetres long. 

The Unit of Current. — ^The unit of current is the 
" ampere." It is the current produced when an electro- 
motive force of I volt acts through a resistance of 
I ohm. The strength of a current depends upon the 
electro-motive force and resistance. If the electro-motive 
force is increased, the current will be increased ; if the 
resistance is increased, the current will be diminished. 
In other words, increase of the force that produces the 
transfer of the electric fluid (or electrons) will cause a 
larger quantity of electric fluid (or electrons) to pass 
along the circuit, while increase of the resistance to the 
passage of the fluid (or electrons) will lessen the quantity 
of fluid (or electrons). 

The relation between strength of current, electro- 
motive force and resistance is stated in Ohm's law. 

Ohm's Law. — Ohm's law is as follows : — The current 
varies directly as the electro-motive force and inversely 
as the resistance. 



276 ESSENTIALS OF MEDICAL ELECTRICITY 
Expressed in symbols it is : 



c 


= ^ where 


c = 


The current. 


E = 


Electro-motive force. 


R = 


Resistance. 


From the above 


equation we obtain 




E = CR 


and 






■< = ? 



so that with any two of the factors given, the value of 
the third is obtainable by a simple calculation. This is 
probably the most important law that has been laid down 
relating to electricity, and is one that the student should 
be thoroughly familiar with it in all its aspects. It 
underlies every intelligent application of the electrical 
current in mediciue. 

Other Practical Units. — (i) Unit of Quantity. — ^This is 
the " coulomb " and represents the quantity of electri- 
city corresponding to a current of i ampere flowing for 
one second. 

(2) Unit of Work. — The unit of the work done is known 
as a watt. It is the product of the volts and the amperes. 
A current of i ampere at a pressure (E.M.F.) of i volt 
flowing for one hour is called one watt hour. The Board 
of Trade unit, as used by all supply companies, is 1000 
watt hours. A current of 10 amperes at 100 volts flow- 
ing for one hour represents 1000 watt hours, for which 
the usual charge is sixpence. This is not a unit used in 
medical electricity, but, as many will obtain their supply 
from the street mains, it is as well to know what a Board 
of Trade unit really means. 

(3) Unit of Capacity. — It was previously mentioned 



INTERNAL RESISTANCE 277 

that the capacity of a conductor was measured, not by its 
surface area, but by the quantity of electricity required 
to raise its potential from zero to unity. If a coulomb is 
required to raise the potential of a conductor i volt, that 
conductor is said to have a capacity of i farad. The 
size of such a conductor would be so enormous that the 
microfarad — that is, one-millionth of a farad — is taken as 
the unit of capacity. 

Internal Resistance. — This refers to the resistance to 
the flow of current inside a generator or originator of an 
electro-motive force. In the case of a dynamo-electric 
machine it is the resistance of the copper conducting wires 
with which the machine is wound — and in the case of the 
battery it is the resistance of the solution between the 
plates. In the former case it depends on the length and 
size of the wires ; in the latter, on the nature of the solu- 
tion, the area of the plates, and their distance from each 
other. For a generator to produce a large current it is 
essential that its internal resistance be kept very low. A 
resistance inside a cell has to be overcome just the same 
as if it were in the external circuit, and where the external 
resistance is very low, a high internal resistance would 
have a very serious effect on the output of current. On 
the other hand, with a very high resistance in the external 
circuit the internal resistance does not signify very 
much on account of the small proportion it bears to 
the total resistance of the circuit. To take an example : 
if the internal resistance of a cell be 3 ohms, and the 
resistance of the external circuit be i ohm, three-fourths 
of the E.M.F. of the cell will be used up in overcoming 
its own resistance, leaving only one-fourth of the original 
E.M.F. available for the outer or useful circuit. If, again, 
the internal resistance be the same, and the external 
resistance be 97 ohms, then only -^ of the E.M.F. will 
be used up inside the ceU, leaving -^-^ available for the 



278 ESSENTIALS OF MEDICAL ELECTRICITY 

outer circuit. In the first example 75% of the total 
E.M.F. was wasted in the cell, in the second only 3%. 

Arrangements of Cells. — ^If we have a number of cells 
of any kind we can join them up in various ways to suit 
our requirements. Suppose we have twelve ceUs, each 
of which is capable of supplying a current of i ampere at 
an E.M.F. of i volt. It will be more convenient for the 
sake of clearness to assume that the cells have no internal 
resistance. We will also suppose that we have a 12-volt 
incandescent lamp with which we wish to examine some 
part or cavity of the body. This lamp requires an E.M.F. 
of 12 volts to bring it to full incandescence. To obtain 
this we join the positive pole of the first cell to the 
negative of the second, and the positive of the second to 
the negative of the third, and so on to the end of the row, 
so that we have a free positive pole at the first ceU, and a 
free negative pole at the twelfth, thus : — 

Fig. 65. — Diagram of Twelve Cells joined in Series 

If we now connect a volt -meter to the two wires from the 
ends, the instrument wiU register 12 volts, and if we 
replace the volt-meter by the lamp it will light up to its 
full candle-power. 

The cells as arranged above are said to be connected in 
series, and the effect of the arrangement is to increase the 
voltage directly as the number of cells — ^the total E.M.F. 
being equivalent to the E.M.F. of one cell multiplied by 
the number of cells. It does not increase the number of 
amperes beyond what is available from a single cell — 
that is, I ampere, which is probably more than the 
lamp requires. Now suppose we have a cautery which 
has a resistance of y\ ohm and requires a current of 
12 amperes to bring it to the proper heat. It is quite 



ARRANGEMENT OF CELLS 279 

clear that the series arrangement will not do, as the 
amount of current available is quite insufficient to affect 
the cautery. Also it will be seen that an E.M.F. of i volt 
is all that is necessary to send a current of 12 amperes 
through a resistance of ^^ ohm. Thus we have no object 
in increasing the voltage beyond that given by one cell, 
but the amperage of the current must be increased till 
it reaches 12. We now join all the positive poles together 
and do the same with the negatives, thus : — 



Fig. 66. — Diagram of Twelve Cells joined in Parallel 



+ 



The result here is the same as if we had one big cell 
twelve times the capacity of a single cell. The voltage 
of any given cell is the same whatever the size, but the 
larger the cell the greater the quantity of current it is 
capable of suppling. We will now find that the differ- 
ence of potential between the terminals of the arrange- 
ment is just I volt, but a current of 12 amperes can be 
obtained, so that if we connect up the cautery it will glow 
a bright red and be ready for use. The cells connected 
as above are said to be arranged in parallel. 

Various combinations of the series and parallel arrange- 
ments are also possible. If we wanted a current of 2 am- 
peres at a pressure of 6 volts,' we would arrange the 
first six cells in series, and also the second six cells in the 
same way, and then join these two sets in parallel. This 
is a series-parallel arrangement — other modifications of 
which will suggest themselves. 

Current Density. — ^When a current flows along a 
narrow conductor its density or " concentration " will be 
greater than that of the same current when it flows along 
a broad conductor. The density of a current in one 



28o ESSENTIALS OF MEDICAL ELECTRICITY 

conductor is the strength of the current divided by the 
cross-sectional area. It is of great importance, when apply- 
ing currents to the body, to avoid too great a density. 
The amount of current that the body can tolerate depends 
upon the degree of stimulation of the sensory nerve - 
endings in the skin and the force of contraction of 
the underlying muscles. The greater the density, the 
stronger the stimulation and the more violent the con- 
traction. So if the current enters and leaves the body 
through small electrodes, only weak currents can be 
passed. If we wish to employ large currents we must 
use large electrodes, and see that they are weU adapted 
to the part . For example, if we wished to apply a current 
of 50 milUamperes to a limb, and used electrodes, say, one 
square inch in area, the patient would experience a very 
sharp pain at the points of contact, and if the appHcation 
be persisted in for some minutes, a blister or even an 
ulcer will eventually form. The reason is that the whole 
50 milliamperes passes through an area of one square inch. 
If we use larger electrodes, say five inches by five inches, 
the current density, instead of 50 milliamperes per square 
inch, would be only 2 milliamperes per square inch. 
In this way we can employ the same amount of current 
without discomfort or harm to the patient. 

Electric Current and Magnetism. — ^There is one other 
peculiar manifestation of electricity when passing 
through a conductor that has not yet been mentioned. 
If we take a wire through which a strong current is 
passing, dip it into some iron filings and then remove it 
therefrom (the current still flowing), some of the filings 
will be found attached to the wire, and will not all fall off 
when the wire is shaken, but if we stop the current flow- 
ing they all fall away at once, and so long as the current 
is not flowing the wire will not pick up any more. The 
reason for this is," that when an electric current flows 



MAGNETISM 281 

through a wire there is always a field of magnetic force 
surrounding it. The lines of magnetic force are at right 
angles to the direction of flow of current. This magnetic 
field is a necessary accompaniment of an electric current, 
and is inseparable from it. It is the presence of this 
magnetic field which causes the magnetic needle to be 
deflected in the way to be described later. 

The Magnetic Needle. — ^If a straight piece of hard steel 
wire, such as a knitting needle, be magnetised, and sus- 
pended so as to be free to move in any direction, it will 
gradually come to rest, with one end pointing to the north 
and the other to the south. These ends are called the 
North Pole and South Pole respectively, and one is a 
necessary accompaniment of the other. That is to say, 
if we take any piece of magnetic substance, one end of 
which shows the presence of magnetism of the north 
variety — ^then the other end will be also magnetic, but 
of the south variety. If we take a bar magnet and cut it 
through at the middle where the magnetic attraction 
seems weakest or even lost, the result is two complete 
magnets, each having a north and a south pole. 

The knitting needle arranged as above is merely 
another form of compass, and both are really bar 
magnets. 

Properties of Magnets: Attraction and Repulsion. — 

Magnets possess properties analagous to those of electri- 
fied bodies. Like magnetic poles repel one another ; 
unlike poles attract each other. A magnet is also able 
to induce magnetism in a piece of iron or steel that is 
brought near to it without actually touching it. Any 
one pole of a magnet wiU induce magnetism of an opposite 
kind in that part of the iron that is nearest to it, and of 
the same kind in that part that is farthest away. It 
is for this reason that magnets attract particles of steel 
or iron. Magnetism is induced in them — that of the same 



282 ESSENTIALS OF MEDICAL ELECTRICITY 

kind being farther off than that of the opposite kind, so 
that the particles are attracted with a greater force than 
that with which they tend to be repelled. It will be 
remembered that electrified bodies also attract other light 
bodies, because changes are induced on them. 

Lines of Magnetic Force. — ^Particles of iron or steel and 
magnetic needles, when brought into the neighbourhood 
of a magnet, at once arrange themselves in definite lines. 



/ 



// / 



! / / 









.,?m 



H 



Fig. 67. — Lines of Force around a Bar Magnet 

Magnetism is induced in them, and they take up posi- 
tions determined by the resultant of the attracting and 
repelling forces. The lines along which the magnetic 
induction acts are known as the " lines of magnetic 
force." As the pole of a magnet is approached, the force 
of induction increases and we speak of an increased 
number of lines of force in the region of the poles. A 
magnet is surrounded by lines of force. Fig. 67 shows 
a bar magnet with the surrounding lines of force. If 
two magnets are brought into the neighbourhood of one 
another they tend to arrange themselves so that their 
lines of force assume the same direction where they 
overlap. If a magnetic needle is suspended it sets 
itself north and south, so that its own lines of force 



GALVANOMETER 283 

— ^the majority of which lie between its two poles — may 
coincide with those of the earth. 

It has been mentioned that a wire along which a 
current is flowing is surrounded by a magnetic field. 
The lines of force have a definite direction. They are 
arranged concentrically around the wire conveying the 
current in a plane at right angles to it. If a magnetic 
needle is placed close to a wire along which a current is 
flowing, the north-south direction previously taken under 
the influence of the earth's magnetic lines is now altered 
by the new magnetic lines created by the current. The 
magnetic needle now alters its direction so that its own 
lines of force can coincide as far as possible with those 
created by the current. The position which the north- 
seeking pole of the needle will assume can be foretold if 
the following illustration is remembered : — 

Imagine a man swimming in the wire in the same 
direction as the current and turned so as to face the 
needle, then the north-seeking pole of the latter will be 
deflected towards his lejt hand. 

The Galvanometer. — ^This is an instrument designed 
for the measurement of electrical currents. An ampere- 
meter (or ammeter) is a galvanometer graduated so as to 
indicate on its scale the number of amperes passing 
through it. A milliampere-meter indicates the current 
in thousandths of an ampere, i milliampere being y^Vo^^ 
of an ampere. 

A volt-meter is a galvanometer that measures electro- 
motive force. 

These instruments work on the principles described 
above ; the current causes the deflection of a movable 
magnetic needle, and the amount of deflection is the 
measure of the strength of the current. 

Until comparatively recently all galvanometers were 
of the magnetic needle type. While undoubtedly 



284 ESSENTIALS OF MEDICAL ELECTRICITY 

accurate, they laboured under certain disadvantages. 
They had to be carefuUy levelled, and placed in proper 
relation to the magnetic meridian to bring the pointer 
to zero. The latter always took some time to come to 
rest, and the readings were easily disturbed by the 
presence of magnetic bodies near by. It is not necessary 
to refer to them further, as they are being displaced by 
instruments of the " moving coil " type, one of which is 
shown in Fig. 68. 

Whereas in the original form of instrument the 
magnetic needle was movable and the wire conveying the 

current stationary, in 
the moving-coil form 
the reverse arrange- 
ment is seen. The 
magnet — ^which is 
U-shaped — is station- 
ary, and between its 
poles is the coil of 
wire that conveys the 
current. This coil is 
movable and to it is 
attached an indicatoi 
t^^ that moves over a 
scale calibrated to 
indicate the number of milliamperes. 

These instruments read accurately in any position, 
are quite independent of the earth's magnetism or the 
presence of magnetic bodies, and they are " dead beat " — 
that is to say, the pointer quickly indicates the amount of 
current passing, without first swinging to and fro for 
some time. The instrument shown reads to 15 miUi- 
amperes. As this is too small for some purposes, it is 
provided with one or more shunts, which can be switched 
on or off as desired. The principle of the shunt is 
that when a current has two paths in which to flow, 




Fig. 68. — Milliampere-meter 
" Moving Coil " Type 



MILLIAMPERE-METER 



285 



it divides itself between the two, so that the current 
strength in each path is inversely proportional to its 
resistance. The arrangement is shown diagrammatically 
in Fig. 69. 

As there shown, all the current that passes through 
the instrument will flow through the coil which causes 
the needle to move. The resistance of the shunt 
marked 10 is so adjusted that when it is brought into 
circi^ -^Q of the total current passes through it, and —^ 
through the coil controlUng the needle. Therefore the 
total current passing will be ten times that indicated 
by the instrument. If 
the other shunt is used 
the readings are to be 
multiplied by 100. The 
knob on the top of 
Fig. 68 is for switching 
the shunts in or out 
of circuit. As it is re- 
volved, the figures i, 
10, 100 pass in suc- 
cession behind a small 
opening in the top of the 

dial, indicating which Fig. 69.— Arrangement of Shunts in 
Shunt is in circuit. In Milliampere-meter 

some instruments, however, the figures indicate the 
maximum current recorded when that particular shunt is 
in circuit. In the instrument shown in Fig. 68, the number 
150 is shown, and it means that the instrument now 
records between zero and 150 milliamperes. When the 
zero is showing it means the whole instrument is out 
of action. In this position it is impossible for the 
instrument to be injured by the accidental passage 
of a heavy current through it, which would probably 
cause serious, if not irreparable, damage. Shunted 
instruments are very little more expensive than plain 




i—wHwrnmiQ 



286 ESSENTIALS OF MEDICAL ELECTRICITY 

ones, and should always be selected when buying an 
outfit. 

The Electro-magnet. — ^It was shown that a wire carry- 
ing an electric current became magnetic and would 
attract iron filings. If we take a piece of soft iron rod 
and wrap this wire around it, it will impart its magnet- 
ism to the iron, which will become strongly magnetic, 
especially if the wire is wrapped many times round and 
a strong current sent through it. This arrangement 
constitutes an "electro-magnet." An electro-magnet is 
only magnetic when an electric current is traversing its 
wire helix, provided the core — as it is called — ^is com- 
posed of sojt iron or soft steel. Magnets on this principle 
can be made capable of hfting many tons' weight. They 
lose their magnetism entirely when the current is cut off. 
If the core should be made of very hard steel, a portion 
of the magnetism remains after the current is cut off. 
This core may be removed from the centre of the wire 
winding, and will retain more or less of its magnetism 
indefinitely. In this way permanent magnets are made. 

Electro-magnetic Induction. — ^The first observations of 
this most interesting and important subject were made 
by Faraday. He found that in a closed circuit an electric 
current of momentary duration is induced when a magnet 
is approached to this conductor or withdrawn from it. He 
also found that if a current were made to pass through 
another circuit near, but quite detached from, the first one, 
a momentary current passed through the latter, both when 
the current started and when it was interrupted. The 
current is produced by virtue of the magnetic field set up 
and removed in the neighbourhood of the original closed 
circuit. These induced currents, as they are called, only 
appear so long as the magnetic field is varying in strength. 
The current induced at the starting of the inducing 
current is in an opposite direction to the latter, while that 



SELF-INDUCTION 287 

produced when the inducing current is interrupted is in 
the same direction as the inducing current. It will thus 
be seen that whether we use a permanent magnet, an 
electro-magnet or a length or coil of wire carrying a 
current for our purpose, so long as we subject a closed 
circuit to a varying field of magnetic force, currents of 
electricity are set up in the closed circuit. These currents 
wiU vary in direction of flow according as the magnetic 
field is increasing or decreasing in strength. 

Simple as the fundamental principle of the induction 
of currents is, it is perhaps the most important of all 
as regards the practical appHcations of electricity. The 
dynamo, motor, induction coil, telephone, etc., are all 
based on the principle of electro-magnetic induction. 

Self-induction. — Take a length of insulated copper 
wire, say two or three yards, straighten it out and attach 
one end to one terminal of a cell possessing high internal 
resistance, such as a Leclanche ceU. Bring round the 
other end (both ends must be stripped of their insulating 
covering for an inch or so) and touch the other terminal 
of the cell with it for a moment. A very tiny spark will 
be seen at the instant the wire leaves the terminal. It 
may be necessary to do this experiment in a darkened 
room, so small is the spark. 

Now coil up this length of wire into a close spiral by 
winding it on a ruler, and repeat the experiment. At the 
moment when the circuit is broken and the current 
ceases to flow, a spark that is distinctly brighter will be 
seen at the point where the circuit is interrupted. This 
is the result of the induction of new currents in the turns 
of the spiral at the moment the original current ceases to 
flow. These new currents flow in the same direction as 
the latter, and so reinforce it. A brighter spark is 
therefore produced. At the moment when the circuit is 
completed, new currents are again induced, but these flow 



288 ESSENTIALS OF MEDICAL ELECTRICITY 

in a direction opposite to that of the original current, 
and so weaken it. The weakening is only momentary, 
because the induced currents flow only for a moment, 
and therefore all that they do is to retard the rise of the 
original current to its full strength while they are flowing. 

The development of induced currents in the same 
circuit as that in which the inducing current is flowing 
is spoken of as " Self-induction. " If we introduce a rod 
of iron into the spiral, and the experiments are repeated, 
the effects described above will be further increased. 
Stronger currents will be induced at make and at break 
of the circuit and wiU further weaken the inducing 
currents at make and further reinforce it at break. 

We can vary the amount of this self-induced current 
by increasing or decreasing the number of turns in the 
spiral, by varjdng the strength of the original current, 
and by inserting or withdrawing an iron core. 

The Alternating Current. — ^The current of which we 
have been speaking up to the present is the constant 
current, the current that is flowing continuously always 
in the same direction and with strength unvaried. An 
alternating current is one that is constantly reversing 
its direction of flow. The reversals may be rhythmic 
or arrhythmic, regular or irregular, gradual or abrupt, 
frequent or infrequent. Fig. 9 (p. 23) is a graphic repre- 
sentation of an alternating current of which the reversals 
are rhythmic, regular, gradual and frequent. When an 
alternating current is spoken of without further quaUfi- 
cation it is usually understood to be of the type repre- 
sented in the figure. From A io B the current rises 
from zero to its maximum ; from ^ to C it falls again to 
zero. From C to D the current again rises from zero 
to maximum ; from D to £^ it falls again to zero. From 
C to £ the current is flowing in the opposite direction. 
The complete course, from A to E, is spoken of as one 



ALTERNATING CURRENTS 



289 



complete cycle or phase. The height of the curve 
above the base line at any one spot is proportional 
to the voltage and the length along it to the time 
intervals. The alternating current is produced by a 
dynamo, and it will be seen in the next paragraph how 
it is generated. These currents are frequently named 
" sinusoidal," because their graphic representation is 
approximately a sine curve. In many districts the town 




A r^ CD 

Fig. 70 — To illustrate way in which an Alternating 
Sinusoidal Current is produced 

supply is an alternating current (AC). In others it is 
a constant or " direct " crruent (DC). 

The Production of Alternating Currents. — ^When a coil 
of wire is made to revolve in a magnetic field an electrical 
current will flow round the coil. On this principle 
currents are generated by the dynamo.- 

In Fig. 70 (A), a magnet is shown, and between its 
poles is a single coil of wire. This coil rotates in the mag- 
netic field between the poles of the magnet. During its 
rotation, when it is in the position shown in the figure (A), 
equidistant from both poles, no current flows around it. 
During its rotation through a right angle (one quarter of 
a complete revolution) a current flows around it, start- 
ing from zero, its strength gradually increasing and 

T 



290 ESSENTIALS OF MEDICAL ELECTRICITY 

attaining its maximum value when the coil has the 
position shown in Fig. 70 (B). During the next 
quarter of a revolution the current gradually falls again 
to zero. During the third quarter the current again 
increases to a maximum, and during the fourth quarter 
it gradually reaches zero again. The current that flows 
during the last two quarters of the revolution is in the 
reverse direction. For the first half of the revolution the 
current is in one direction ; for the second half it is in 
the opposite direction. During each half it starts from 
zero, reaches a maximum and again falls to zero. This 
current is the alternating current described in the 
previous paragraph, and may be graphically represented, 
as in Fig. 9. The curve shown, ABCDE, corresponds 
to one complete revolution of the coil. The number 
of these complete cycles per second depends upon the 
rate of revolution of the coil. The " frequency " or 
" periodicity " of an alternating current refers to the 
number of these complete revolutions per second. 
Thus if the periodicity of the current is 100, the coil 
is revolving 100 times per second ; the length of the 
curve recording one complete cycle would be yJir'th of 
a second, and there would be 200 reversals of direction 
(or alternations) each second. 

While it is possible to evolve a sinusoidal current from 
an ordinary battery, we may say that all alternating 
currents have their origin in dynamo machines. The 
number of cycles per second — i.e. the frequency— of 
these currents used to be 100 to 130, but of late, lower 
frequencies have become more common — from 40 to 60. 

The Dynamo. — It may be said that over 99% of the 
electricity used for various purposes is obtained from 
dynamos. By far the most convenient source of electri- 
city for medical purposes is the dynamo at the power 
station, from which the supply is taken along the mains 



DYNAMO 



291 



to the places where it is desired. In places where there 
is no main supply, the current may be derived from a 
small dynamo worked by a gas or oil engine or by Water- 
power. 

The device which has been described above for the 
production of an alternating current is really a dynamo 
in a very simple form. A dynamo consists of three 
essential parts : (i) the field magnet ; (2) the armature ; 
(3) the current-collecting device (Fig. 71). 

(i) The Field Magnet, which generally forms part of 
the framework of the machine, is usually an electro- 




ARMATURE 

BRUSH ^ 

_ " ARMATURE 

COMMUTATOR •<■ 

" FIELD MAGNET 



FIELD MAGNET 
COIL 



Fig. 71. — Dynamo constructed to generate a Direct Current 

magnet, the poles of which have their opposing faces 
hollowed out to the arc of a circle, in which space the 
armature revolves. When the field magnet is excited 
this space will be th^ seat of a powerful magnetic field. 
The essential point about the field magnet is that its 
poles never change ; one is always north and the other 
south. 

(2) The Armature is the part of the dynamo in which 
the current is induced by reason of its movement in the 
magnetic field. In the simple device shown in Fig. 70 
it was a single circuit of wire. The armature of a dynamo 
that generates alternating currents consists of an axle 



292 ESSENTIALS OF MEDICAL ELECTRICITY 

surrounded by strips of soft iron, upon which are wound 
several turns of insulated copper wire. The free ends 
of this* wire are connected to the current-coUecting 
device. 

The armature of a dynamo that is to generate a current 
that flows in the same direction and with constant 
strength (the constant current, or direct current) con- 
t ains several separate coils. 

(3) The Current- collecting Device. — ^If an alternating 
current is to be collected the device consists of two metal 
rings mounted concentrically on the axle of the armature. 
They are insulated from each other and the axle. To 
one of them is fixed one of the free ends of the wire 
wound round the armature, to the other ring is fixed the 
other free end. A carbon " collecting-brush " presses 
against each ring and leads the current to the main 
circuit. As the axle of the armature revolves, the rings 
revolve with it, and the carbon brushes coUect the current 
from the rings. The current collected is an alternating 
current. 

If a constant (direct) current is to be collected the 
collecting device (called in this case a " commutator ") 
consists of a number of copper bars mounted in the form 
of a cylinder, and insulated from the shaft and from each 
other. There are as many bars as there are coils on the 
armature. The beginning of one coil and the end of the 
coil just preceding it are joined together, and the two are 
attached to a commutator bar. Two brushes of copper 
gauze or carbon press against the revolving cylinder and 
collect the current (see Fig. 71). 

Dynamos and Motors: Motor Transformers. — The 

dynamo that generates a direct current is a reversible 
machine. That is to say, if another direct current is sent 
through the armature, the latter will revolve. The 
dynamo, therefore, now acts as a motor, converting 



MOTOR TRANSFORMER 293 

electrical into mechanical energy. Motors are also con- 
structed so as to work when supplied by an alternating 
current. Electric motors are used in medicine for several 
purposes, for working drills and trephines, for applying 
massage and vibration, etc. 

Electric motors are used for another purpose. They 
can be used to work dynamos constructed to generate a 
new current of a kind different from that which works the 
motor. A combination of a motor and dynamo for this 
purpose is called a "motor transformer." A motor 
transformer is an exceedingly useful machine and is 
extensively used now in electro-medical work. It serves 
the following purposes : — 

(i) A constant (direct) current — from the main or 
from accumulators — can be converted into an alternating 
(sinusoidal) current. 

(2) An alternating current can be converted or trans- 
formed into a direct current. 

(3) By combining a motor and a dynamo it is possible 
to convert a direct current at a high voltage into another 
direct current at lower voltage. By such an arrangement 
the circuit in which a patient is placed can be kept dis- 
tinct and separate from the main circuit, so that the risk 
attending the use of the direct current from the main for 
medical purposes is avoided. 

A motor transformer is constructed on the following 
plan : — On the lengthened axis of a motor is fixed another 
independent armature, which revolves between the poles 
of another field magnet. The armature and the current- 
collecting device can be arranged so that the new current 
is either alternating or direct, while the number of turns 
of wire on the armature will determine the voltage and 
amperage of the new current. 

It is not essential to have an independent field magnet 
and armature. The other armature may have two 
separate sets of windings on it, forming a double 



294 ESSENTIALS OF MEDICAL ELECTRICITY 



armature, and the same magnetic field will serve for this 
double armature. 

Static Transformer.— A motor transformer can be used 
for the purpose of converting an alternating current into 
another alternating current with a different voltage and 




laOHCOfi^ 



SbcondaryCoil 

Fig. 72. — Plan of a Static Transformer 

amperage, but a much more efficient and less costly 
apparatus for the purpose is the " static transformer." 
It is called a static transformer because there are no 
moving parts. It consists of a core of soft wire made 
in the form of a ring or a square (Fig. 72). A coil of 
insulated wire is wound around one side. Another 
independent coil, also of insulated wire, is wound on the 
opposite side. The alternating current is led through one 
of these coils. As it alternates backwards and forwards a 
varying magnetic field is set up in the core ; as a result, new 



STATIC TRANSFORMER 295 

alternating currents are induced in the other coil. The 
latter coil is known as the secondary coil, to distinguish 
it from the other coil, which is known as the primary coil. 
The voltage and amperage of the current that is induced 
in this secondary coil depends on the number of turns it 
contains as compared with the number of the primary. 
To take an example. Suppose that the primary coil 
has 100 turns of wire and that the alternating current 
supplied to it has a pressure of 100 volts, and that we 
wish to obtain a current to heat a cautery which requires 
a pressure of, say, 5 volts. The primary has one turn per 
volt and theoretically the same will be right for the 
secondary — in this case five turns. It will be found that 
this will come out about right, and if the wire of the 
secondary has been chosen sufficiently thick plenty of 
current will be available for even the largest cautery used 
in surgery. A transformer regulates itself in a most 
perfect manner. 

As we draw off current from the secondary this relieves 
the primary of so much of its self-induction, and 
consequently more current flows in. In a well-designed 
transformer very nearly the same amount of energy is 
available from the secondary side as is supplied to the 
transformer on the primary side. Supposing we have one 
which is designed to take 10 amperes at 100 volts through 
the primary. This is equivalent to 1000 watts. Accord- 
ing as the secondary is wound we can have from it 200 
amperes at 5 volts, i ampere at 1000 volts, or o-i ampere 
at 10,000 volts. The alternating current transformer is 
the most efficient instrument we possess. For those who 
have an alternating current available, a transformer 
which will give any voltage desired is a most useful 
appliance and will well repay any trouble or expense 
incurred in obtaining it. 



INDEX 



Accumulators, 270 ; construc- 
tion of, 271 ; charging of, 59, 

271 
Acne Vulgaris, 214 
Acroparsesthesia, 215 
Action of electricity on tissues, 

3 et seq. 
Alopecia, 215 
Alternating current, 21, 23, 288 ; 

production of, 289 ; periodicity 

of, 290 
Aluminium rectifier, 51 
Amenorrhcea, 215 
Ampere, 275 

Ampere-meter (ammeter), 283 
Ampere-meter, hot wire, 167 
Anal fissure, 215 
Aneurysm, 97, 215 
Anode, 68 

Anodic closure contraction, 143 
Anterior poliomyelitis, 218 
Antrum, ionisation of, 84 
Aphonia, 216 
Apostoli, method of, 96 
Arm, palsy of, 129 
Arm baths, iii 
Armature of condenser, 261 ; of 

dynamo, 291 
Arrangement of cells, 278 ; in 

series, 278 ; in parallel, 279 
Arthritis, 216 ; gonorrhoeal, 217 ; 

gouty, 217 ; osteo-, 218 ; 

rheumatoid, 217; traumatic, 

216 
Asthma, 219 
Ataxy, Locomotor, 232 
Auto-condensation couch, 169 
Auto-conduction, 170 

297 



Baker electric machine, 199 ; 

field regulator, 206 
Bar magnet, 281 
Bath, electric, iii et seq. (see 

also Electric Baths) ; Schnee, 

112 
Bipolar electric bath, 114 
Bipolar electrolysis needles, 92 
Blood-pressure, high, 228 ; low, 

13, 210 
Boils, 219 

Bougie electrode, 95 
Breeze, static, 208 
Brush, static, 208 



Capacity, 260 

Carbuncle, 219 

Carcinoma, 219 

Cardiac failure, 220 

Cataphoresis, 71 

Cell, bichromate, 269-272 ; dry, 

270 ; Leclanche, 269 ; Poggen- 

dorff, 269, 272 
Cells, arrangement in parallel, 

278 ; series, 278 
Cerebral galvanisation, 9 
Chemical changes produced by 

electricity, i-io, 14 
Chilblains, 220 
Chorea, 220 
Closure contraction, 10 
Coil, induction, 27 
Colitis, 221 

Collector, current, 62 
Colon, ionisation of, 85 



298 



INDEX 



Commutator, of dynamo, 292 ; 
Ruhmkorft, 21 

Compass needle, 281 

Condenser, 261 ; couch, 169 ; 
discharge of, 161, 262 ; elec- 
trode, 171 

Condensers, testing by discharge 
of, 158 

Conducting cords, 77 

Conduction of currents at high 
voltage, 70 ; through body, 4 ; 
through solution, 3 

Conductors, 255 

Congestion, 221 

Conjunctivitis, Vernal, 248 

Current, alternating, 23, 288 ; 
collector, 62 ; conduction 
through body, 4 ; solutions, 3 ; 
conduction at high voltage, 70 ; 
constant, 16, 273 ; continuous, 
16 ; density of, 279 ; density 
of, in body, 67 ; direct, 16, 273 ; 
faradic, 26 ; for treatment of 
paralysis, 120 ; from main, 35 ; 
from main (direct), 36 ; from 
main (alternating), 46; dangers, 
52 ; from main for baths, 49 ; 
from main for cautery, 42, 48 ; 
from main for lamps, 44, 48; 
galvanic, 16, 273 ; high-fre- 
quency, 161 ; measurement of, 
273 ; modifications of, 16 et 
seq. ; Morton wave, 205 ; path 
in body, 66 ; production of, 
264, 289, 290 ; simple alternat- 
ing, 21 ; simple interrupted, 
I 7 ; sinusoidal, 23 ; slow sinu- 
soidal, 25 ; sources of supply, 
35 et seq. ; static induced, 212 ; 
static wave, 205 ; unit of, 275 



Dangers in use of main current, 

52 
Density of static charge, 259 ; 

current, 279 
Diagnosis, use of currents for, 

138 et seq. 



Diathermy, 178 et seq. ; appa- 
ratus, 182 ; application to body, 
185 ; coagulation of tissues by, 
190 ; condenser couch for, 185 ; 
electrodes for, 187, 189, 191 ; 
general treatment by, 185 ; 
heating of deep parts by, 184 ; 
and innocent growths, 193 ; 
and inoperable growths, 192 ; 
and malignant growths, 192 ; 
and metabolism, 184; medical, 
189 ; and operable growths, 
193 ; physiological action of, 
183 ; production of, 179 

Discharge of Leyden jar, 161, 
262 ; of condenser, 161, 262 



Effluve, high-frequency, 170 

Electric baths, 1 1 1 ; bipolar, 1 14 ; 
construction of, 11 1 ; currents 
for, 115; dangers of, 57; 
electrodes for, 114 ; full length, 
113 ; how given, 115 ; pre- 
cautions in giving, 116; 
Schnee, 112 ; unipolar, in 

Electric supply, sources of, 35 
et seq. 

Electrical reactions, testing of, 
138 et seq. ; types of, 149 et 
seq. ; treatment, index of, 214 
et seq. 

Electricity, nature of, 252 ; 
theories of, 253 

Electrisation, general, 117 

Electrodes, bougie, 95 ; con- 
denser, 171 ; diathermy, 187,- 
189, 191 ; high-frequency, 171; 
paddle, 114 ; static, 201 ; 
static wave, 207 ; vacuum, 172 

Electrolysis, surgical, 8, 88 ^/ seq.; 
linear, 96 

Electrolytic incision, 96 

Electro -magnet, 286 

Electro-magnetic induction, 286 

Electro-motive force, 273 

Electrons, 253 

Electroscope, 257 

Endometritis, 225 



INDEX 



299 



Enlargement of prostate, 244 
Epididymitis, 241 
Epilation, 89 ; needle, 90 
Episcleritis, 225 
Erb's point, 132 
Ewing's reverser, 25 
Exophthalmic Goitre, 226 



Facial paralysis, 126 
Farad, 261 

Faradic current, 26 ; how pro- 
duced, 27 ; variations in, 30 
Faradisation, general, 117 
Fibromyomata, 96 
Fibrositis, 226 
Field m.agnet, 291 
Fissure, anal, 215 
Fistula, 226 
Fulguration, 177 
Furuncle, 219 



Galvanisation, cerebral, 9 ; 
general, 117 

Galvano-faradisation, 117 

Galvanom.eter, 283 

General faradisation, 117; gal- 
vanisation, 117 

Generator, motor, 45 

Goitre, exophthalmic, 226 

Gonorrhcea, 226 

Gonorrhoeal arthritis, 217 

Gouty arthritis, 217 

Growths, malignant, 97, 192, 233; 
innocent, 193 



H 



HEMORRHOIDS (see Piles) 

Headache, 227 

Hemiplegia, 227 

High blood-pressure, 228 

High-frequency currents, 161 et 
seq. ; action of, 174 ; appara- 
tus for, 163 ; application, 168 ; 



High-frequency currents- contd. 
and ionic movement, 11 ; 
meaning of , 11, 161 ; measure- 
ment of, 167; and metabolism, 
175 ; mode of action of, 12 ; 
oscillations, 161, 263 ; in 
surgery, 176 ; and vascular 
system, 175 

High-frequency effiuve, 170 ; 
electrodes, 171 

Holtz electric machine, 198 

Hot-wire ampere-meter, 167 

Hypertrichosis, 228 

Hysteria, 229 



Incision, electrolytic, 96 
Incontinence of urine, 229 
Induced current, 286 ; static, 212 
Induction coil, 27 ; currents in, 
29 ; designs of, 32-34 ; out- 
put of, 29 
Induction, electro-magnetic, 286 
Infantile palsy, 134 
Influence machine, 263 ; Baker, 
199; Holtz, 198; mode of 
action, 264; Toepler, 199; 
Voss, 199 ; Wimshurst, 194 
Injuries of joints, 216 
Interrupter, 17, 19, 21, 25 
Ionic medication, 70 et seq. ; 
advantages of, 72 ; apparatus 
for, 75 ; application of, 81 ; 
of colon, 85 ; conducting cords 
for, 77 ; current for, 76 ; of 
deep parts, 99 et seq. ; defini- 
tion of, 71 ; duration of, 86 ; 
electrodes for, 77 ; frequency 
of, 87 ; limitations of, 73 ; of 
maxillary antrum, 84 ; of 
rectum, 85 ; of sinuses, 83 ; 
solutions for, 79 ; surgical, 88 
et sea. 
Ionic migration, 5, 8 
Ionic movement as stimulus, 10 
lonisation (see Ionic . Medica- 
tion) 
lonisation in deep tissues, 99 et 
seq. 



300 



INDEX 



lonisation, surgical, 88 et seq. 

Ions, 4 ; depth of penetration of, 
74 ; direction of migration of, 
5 ; introduction of, g ; migra- 
tion of, 5, 8 ; meaning of, 4 ; 
proof of entry, 72 ; those used 
in medicine, 81 



JoiMTS, diseases of, 216 ; in- 
juries of, 216 



K 



Kathode, 69 ; meaning of, 5 
Kathodic closure contraction, 

143 
J Keratitis, 231 



Lachrymal obstruction, 231 
Leduc's interrupter, 19 
Leyden jar, 261; discbarge of, 

263 
Linear electrolysis, 96 
Locomotor Ataxy, 232 
Longitudinal reaction, 152 
Lupus Vulgaris, 232 



Measurement of current, 283 ; 

voltage, 283 
Median nerve, 131 
Menstrual irregularities, 215, 225 
Mental diseases, 234 
Meralgia Paraesthetica, 234 
Meta tarsalgia, 234 
Metronome interrupter, 18 
Microfarad, 276 
Milliampere, 283 
Milliampere-meter, 283 
Mode of action of electricity, 3 

et seq. 
Modifications of constant current, 

16 
Moles, 95 
Monoplegia, 227 
Monopolar baths, iii 
Morton wave current, 205 
Motor, electric, 292 
Motor generator, 45 
Motor points, 142 
Motor transformer, 45, 292 
Multostat, 25, 45 
Muscle, testing reactions of, 145 ; 

reactions of normal, 138 ; 

types of reaction of, 149 
Myalgia, 235 
Myasthenic reaction, 153 
Myelitis, 235 
Myotonic reaction, 152 



N 



M 



Magnetic attraction and re- 
pulsion, 281 

Magnetic lines of force, 283 ; 
needle, 281 ; poles, 280 

Magnetism, 280 

Magnets, lines of force of, 283 ; 
poles of, 281 ; properties of, 
281 

Main, current from, 38 et seq. 

Malignant growths, 97, 233 

Maxillary antrum, ionisation of, 
84 



N^vus, needles for treatment of, 
91, 92 ; treatment of, 91 et seq. 

Nerve trunks, testing of, 1 49 

Nerves, peripheral, 124 ; reac- 
tions of, 149 

Neuralgia, great occipital, 237 ; 
ovarian, 242 ; trigeminal, 236 

Neurasthenia, 237 

Neuritis, 237 ; alcoholic, 238 ; 
arsenical, 238 ; brachial, 239 ; 
optic, 242 ; rheumatic, 239 ; 
septic, 239 

Nocturnal incontinence, 229 

Non-conductors, 255 

Normal reactions, 139 



INDEX 



301 



o 



Obesiiy, 240 

Occupation spasm, 241 

CEsophageal spasm, 241 ; stric- 
ture (see under Urethral 
Stricture) 

Ohm, 275 

Ohm's law, 275 

Ophthalmia Neonatorum, 242 

Optic neuritis, 242 

Orchitis, 241 

Oscillograph tracings, 30 et seq. 

Osteo-arthritis, 218 

Oudin's resonator, 170 

Ovarian neuralgia, 242 

Ozaean, 242 



Pantostat, 25, 45 
Parallel arrangement of cells, 279 
Paralysis Agitans, 242 ; of arm 
muscles, 129 ; changes in 
muscles in, 119 ; currents used 
in treatment of, 120 ; deltoid, 
128 ; duration of treatment in, 
124 ; electrical reactions in, 
153 ; electrical treatment of, 
118; Erb's, 131; facial, 126; 
infantile, 134 ; of lower limb, 
133 ; median, 131 ; muscle 
changes in, 119 ; musculo- 
spiral, 129 ; of peripheral 
nerves, 129 et seq. ; of sciatic, 
133 ; of serratus ma gnus, 128 ; 
of spina ti, 129 ; of sterno- 
mastoid, 127 ; of trapezius, 
127 ; treatment of, 118 et seq. ; 
ulnar, 131 
Paraplegia (see Hemiplegia) 
Partial reaction of degeneration, 

151 
Path of current in body, 66 
Penetration of ions, 72 ; depth 

of, 74 ; proof of, 72 
Perineuritis, 243 
Peripheral nerve palsy, 124 ; in 

lower limb, 133 ; in upper 

limb, 125 



Physical effects of electricity, 13 

Piles, 243 

Plate of voltaic cell, 268 ; posi- 
tive and negative, 268 

Platform, insulated, 200 

Pleurisy, 243 

Polar reversal, 151 

Polarisation, 269 ; prevention 
of, 269 

Polarity of static machine, 202 

Poles, magnetic, 281 ; negative 
and positive, 268 ; of voltaic 
cell, 268 

Poliomyelitis, 218 

Polystat, 25, 45 

Portable battery, 61 ; shunt 
resistance, 40 

Port- wine marks, 94, 244 

Potential, 259 

Practical units, 275, 276 

Primary batteries, 60 ; coil, 27] 

Private installations, 58 

Prognosis of RD, 156 

Prostate, enlargement of, 244 

Pruritus ani, 244 ; vulvaj, 244 



R 



Raynaud's disease, 245 
Reaction of degeneration, 151 ; 
appearance of, 155 ; complete, 

151 ; course of, 155 ; meaning 
of, 153 ; partial, 151 ; prog- 
nosis of, 156 

Reaction, longitudinal, 152 ; 
myasthenic, 153 ; Myotomi, 

152 ; Rich's, 153 ; types of, 
149 

Reactions, of muscle, 138 ; of 

nerve, 138 ; normal, 139, 149 ; 

testing of, 138 et seq. ; weak 

normal, 150 
Rectal fistula (see Fistula) 
Rectifier, chemical (aluminium), 

51 ; mechanical (motor), 52 
Rectum, ionisation of, 85 
Refreshing action of current, 9 
Resistance, 274 ; of body, 64 et 

seq. ; internal, 277 ; series, 37 ; 

shunt, 37 ; unit of, 275 



302 



INDEX 



Resonator, Oudin's, 170 

Reyn's electrolysis, 232] 

Rheumatic neuritis, 239 

Rheumatoid arthritis, I217 

Rhumkorfi coil, 27 ; commuta- 
tor, 21 

Rhythmic current interrupters, 
17-23 ; ^resistance varyers, 106 

Rich's reaction, 153 

Rickets, 245 

Rodent ulcer, 245 



Sarcoma (see Malignant 

Growths) 
Scar tissue, 246 
vSchnee bath, 112 
Sciatica, 247 

Sclerosis, disseminated, 224 
Secondary coil, 28 ; current, 29 
Self-induction, 287 
Series, arrangement of cells in, 

278 
Series resistance, 37 
Sexual disorders, 248 
Shoulder, paralysis of, 127 
Shunt resistance, 37 
Shunts to milliampere-meter, 2,85 
Simple alternating current, 21 
Simple interrupted current, 17 
Sinuses, ionisation of, 83, 248 
Sinusoidal current, 23 ; slow, 

25 

Skin, resistance of, 64 

Slow sinusoidal current, 25 

Solenoid, 164 

Sources of electric supply, 35 et 
seq. ; from accumulators, 59 ; 
from main, 35 et seq. ; from 
primary batteries, 60 ; from 
private installation, 58 

Spark-gap, diathermy, 181 ; high- 
frequency, 164 

Sparks, static, 210 

Spasms, oesophageal, 241 ; oc- 
cupation, 250 

Sprains (see Arthritis) 

Spring catarrh, 248 



Static bath, 203 ; breeze, 208 ; 
brush, 208 ; charge and dis- 
charge, 205 ; electricity, 194, 
etseq. ; electrodes, 201 ; induced 
current, 212 ; machines, 194- 
200 ; mode of action of, 13, 14 ; 
physics, 253 ; testing polarity, 
202; sparks, 210; transformer, 
47; 294 ; wave current, 205 

Stellate veins, 94 

Stiff joints (see Arthritis) 

Stimulation of tissues, 104 ; use 
of current for, 104 ; how pro- 
duced, 10 

Stricture, treatment of, 95 ; 
urethral, 95 

Superfluous hair, 89 

Supply, sources of electric, 35 
et seq. 

Surgical electrolysis, 8 ; ionisa- 
tion, 8 

Switchboard, 39-42 

Sycosis, 248 

Synovitis, 248 



Tabes (see Locomotor Ataxy) 

Testing polarity, 202 

Testing reactions, apparatus for, 
139 ; by condensers, 158 ; 
difficulties in, 157 ; defects 
of method, 158 ; how done, 141, 

145 
Thermal effects of electricity, 

Tinea, 249 

Tinnitus Aurium, 249 
Toepler machine, 199 
Trachoma, 249 

Transformer, motor, 45 ; static, 
47, 294 



U 

Ulcer, chronic non-specific, 249 ; 

corneal, 224 ; rodent, 245 
Ulnar palsy, 130 
Unipolar baths, 11 1 



INDEX 



303 



Unit of capacity, 2 76 ; of current, 
275 ; of E.M.F., 274 ; of re- 
sistance, 275 ; of work, 276 
Universal apparatus, 25 
Urethra, stricture of, 95 
Urinary incontinence, 229 
Uterine fibromyomata, 97 



Variocele, 250 

Veins, stellate, 94 ; varicose, 250 

Vernal Conjunctivitis, 243 

Volt, 274 

Voltaic cell, 266 

Volt-meter, 283 



W 



Vacuum electrodes, 172 
Variation of resistance, rhythmic, 

106 
Varicose, veins, 250 



VvARTS, 94, 251 
Watt, 276 

Wimshurst machine, 94 
Writer's cramp, 250 



Henry Kimpton, 263 High Holborn, London, 



RETURN TO the circulation desk of any 
University of California Library 
or to the 
NORTHERN REGIONAL LIBRARY FACILITY 
Bldg.400, Richmond Field Station 
University of California 
Richmond, CA 94804-4698 

ALL BOOKS MAY BE RECALLED AFTER 7 DAYS 

• 2-month loans may be renewed by calling 
(510)642-6753 

• 1-year loans may be recharged by bringing 
books to NRLF 

• Renewals and recharges may be made 4 
days prior to due date. 

DUE AS STAMPED BELOW 



[ML 9 2002 



12,000(11/95) 



S ^Si 



/ 




ITY OF CAUFORNIA LIBRARY 



